{"id":12299,"date":"2023-11-12T20:10:33","date_gmt":"2023-11-13T03:10:33","guid":{"rendered":"https:\/\/www.mysqltutorial.org\/?page_id=12299"},"modified":"2023-11-12T20:10:34","modified_gmt":"2023-11-13T03:10:34","slug":"mysql-merge-storage-engine","status":"publish","type":"page","link":"https:\/\/www.mysqltutorial.org\/mysql-administration\/mysql-merge-storage-engine\/","title":{"rendered":"MySQL MERGE Storage Engine"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you will learn about MySQL <code>MERGE<\/code> storage engine and how to use it effectively.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Introduction to MySQL MERGE storage engine<\/h2>\n\n\n\n<p>The <code>MERGE<\/code> storage engine allows you to create a special table called a <code>MERGE<\/code> table that consists of multiple <a href=\"https:\/\/www.mysqltutorial.org\/mysql-administration\/mysql-myisam\/\">MyISAM tables<\/a> with identical column data types.<\/p>\n\n\n\n<p>Once you have the merged table, you can manage multiple underlying MyISAM tables as if they were one table.<\/p>\n\n\n\n<p>In other words, the <code>MERGE<\/code> storage engine is a collection of identical MyISAM tables that can be used as one.<\/p>\n\n\n\n<p>The <code>MERGE<\/code> storage engine is also known as <code>MRG_MyISAM<\/code>.  <\/p>\n\n\n\n<p>The underlying MyISAM tables need to meet the following conditions to participate in a MERGE table:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>All tables have the same number of columns with the same data type in the same order.<\/li>\n\n\n\n<li>All tables have the same indexes in the same order.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Creating a MERGE table<\/h3>\n\n\n\n<p>To create a <code>MERGE<\/code> table, you use the following  <code><a href=\"https:\/\/www.mysqltutorial.org\/mysql-basics\/mysql-create-table\/\">CREATE TABLE<\/a><\/code> statement:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> merge_table_name(\n    column_list\n) <span class=\"hljs-keyword\">ENGINE<\/span>=<span class=\"hljs-keyword\">MERGE<\/span> <span class=\"hljs-keyword\">UNION<\/span> = (t1, t2, ...) &#91;INSERT_METHOD=<span class=\"hljs-keyword\">FIRST<\/span>|<span class=\"hljs-keyword\">LAST<\/span>|<span class=\"hljs-keyword\">NO<\/span>];<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this syntax:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>ENGINE=MERGE<\/code> clause specifies that the table is a <code>MERGE<\/code> table.<\/li>\n\n\n\n<li><code>UNION=(t1, t2, ...)<\/code> allows you to list the MyISAM table for inclusion in the <code>MERGE<\/code> table.<\/li>\n\n\n\n<li><code>INSERT_METHOD<\/code> controls how inserts into the <code>MERGE<\/code> table occur. It has three options: <code>FIRST<\/code>, <code>LAST<\/code>, and <code>NO<\/code>. You use the <code>FIRST<\/code> and <code>LAST<\/code> to instruct the storage engine to insert to the first or last underlying table respectively. If you use <code>NO<\/code>, the storage engine won&#8217;t allow you to insert data into the <code>MERGE<\/code> table.<\/li>\n<\/ul>\n\n\n\n<p>When you create a <code>MERGE<\/code> table in MySQL, it generates a <code>.MRG<\/code> file containing the names of the underlying MyISAM tables, and it also stores the <code>MERGE<\/code> table format in the data dictionary.<\/p>\n\n\n\n<p>MySQL also allows you to create a <code>MERGE<\/code> table that combines underlying tables from different databases.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Removing a MERGE table<\/h3>\n\n\n\n<p>To drop a <code>MERGE<\/code> table, you use the <code>DROP<\/code> <code>TABLE<\/code> statement:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">DROP<\/span> <span class=\"hljs-keyword\">TABLE<\/span> merge_table_name;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>When you drop a <code>MERGE<\/code> table, MySQL drops only the <code>MERGE<\/code> specification and doesn&#8217;t delete the underlying MyISAM tables.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Changing the underlying tables of a MERGE table<\/h3>\n\n\n\n<p>To remap a <code>MERGE<\/code> table to a different collection of MyISAM tables, you can use one of the following methods:<\/p>\n\n\n\n<p>1) Drop the <code>MERGE<\/code> table and re-create it:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">DROP<\/span> <span class=\"hljs-keyword\">TABLE<\/span> merge_table_name;\n\n<span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> merge_table_name(\n   ...\n) <span class=\"hljs-keyword\">ENGINE<\/span>=<span class=\"hljs-keyword\">MERGE<\/span> <span class=\"hljs-keyword\">UNION<\/span>=(t1, t2, ...);<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>2) Use&nbsp;<code>ALTER<\/code> <code>TABLE<\/code>&nbsp;to change the list of underlying tables:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">ALTER<\/span> <span class=\"hljs-keyword\">TABLE<\/span> merge_table_name\n<span class=\"hljs-keyword\">UNION<\/span>=(t1,t2,...);<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h3 class=\"wp-block-heading\">Manipulating data of a MERGE table<\/h3>\n\n\n\n<p>MySQL allows you to perform <code><a href=\"https:\/\/www.mysqltutorial.org\/mysql-basics\/mysql-insert\/\">INSERT<\/a><\/code>, <code><a href=\"https:\/\/www.mysqltutorial.org\/mysql-basics\/mysql-update\/\">UPDATE<\/a><\/code>, <code><a href=\"https:\/\/www.mysqltutorial.org\/mysql-basics\/mysql-delete\/\">DELETE<\/a><\/code>, and <code><a href=\"https:\/\/www.mysqltutorial.org\/mysql-basics\/mysql-select\/\">SELECT<\/a><\/code> on <code>MERGE<\/code> tables. However, you need to have corresponding privileges on the underlying MyISAM tables that map to the <code>MERGE<\/code> tables.<\/p>\n\n\n\n<p>If a user has access to MyISAM table <code>t<\/code>, the user can create <code>MERGE<\/code> table <code>m<\/code> that accesses the MyISAM table <code>t<\/code>. But if the user&#8217;s privilege on table <code>t<\/code> is <a href=\"https:\/\/www.mysqltutorial.org\/mysql-administration\/mysql-revoke\/\">revoked<\/a>, the user continues to have access to table <code>t<\/code> via the merge table <code>m<\/code>. This is the security issue that you need to be aware of when working with <code>MERGE<\/code> tables.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">MySQL MERGE storage engine example<\/h2>\n\n\n\n<p>First, create a new MyISAM table called t1:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> t1(\n   <span class=\"hljs-keyword\">id<\/span> <span class=\"hljs-built_in\">INT<\/span> AUTO_INCREMENT PRIMARY <span class=\"hljs-keyword\">KEY<\/span>,\n   <span class=\"hljs-keyword\">name<\/span> <span class=\"hljs-built_in\">VARCHAR<\/span>(<span class=\"hljs-number\">50<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-literal\">NULL<\/span>\n) <span class=\"hljs-keyword\">ENGINE<\/span>=MyISAM;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Second, create another MyISAM table called t2 with identical columns and data types as the table t1:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> t2(\n   <span class=\"hljs-keyword\">id<\/span> <span class=\"hljs-built_in\">INT<\/span> AUTO_INCREMENT PRIMARY <span class=\"hljs-keyword\">KEY<\/span>,\n   <span class=\"hljs-keyword\">name<\/span> <span class=\"hljs-built_in\">VARCHAR<\/span>(<span class=\"hljs-number\">50<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-literal\">NULL<\/span>\n) <span class=\"hljs-keyword\">ENGINE<\/span>=MyISAM;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Third, insert rows into the t1 and t2 tables:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span> t1(<span class=\"hljs-keyword\">name<\/span>) <span class=\"hljs-keyword\">VALUES<\/span>(<span class=\"hljs-string\">'John'<\/span>);\n<span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span> t1(<span class=\"hljs-keyword\">name<\/span>) <span class=\"hljs-keyword\">VALUES<\/span>(<span class=\"hljs-string\">'Jane'<\/span>);\n<span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span> t2(<span class=\"hljs-keyword\">name<\/span>) <span class=\"hljs-keyword\">VALUES<\/span>(<span class=\"hljs-string\">'Bob'<\/span>);\n<span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span> t2(<span class=\"hljs-keyword\">name<\/span>) <span class=\"hljs-keyword\">VALUES<\/span>(<span class=\"hljs-string\">'Alice'<\/span>);<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Fourth, create a <code>MERGE<\/code> table that includes the MyISAM table t1 and t2:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> t(\n   <span class=\"hljs-keyword\">id<\/span> <span class=\"hljs-built_in\">INT<\/span> AUTO_INCREMENT PRIMARY <span class=\"hljs-keyword\">KEY<\/span>,\n   <span class=\"hljs-keyword\">name<\/span> <span class=\"hljs-built_in\">VARCHAR<\/span>(<span class=\"hljs-number\">50<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-literal\">NULL<\/span>\n) <span class=\"hljs-keyword\">ENGINE<\/span>=<span class=\"hljs-keyword\">MERGE<\/span> <span class=\"hljs-keyword\">UNION<\/span>=(t1,t2) INSERT_METHOD=<span class=\"hljs-keyword\">LAST<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Fifth, query data from the <code>MERGE<\/code> table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">SELECT<\/span> \n  <span class=\"hljs-keyword\">id<\/span>, \n  <span class=\"hljs-keyword\">name<\/span> \n<span class=\"hljs-keyword\">FROM<\/span> \n  t;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\">+<span class=\"hljs-comment\">----+-------+<\/span>\n| id | name  |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n|  1 | John  |\n|  2 | Jane  |\n|  1 | Bob   |\n|  2 | Alice |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n4 rows in <span class=\"hljs-keyword\">set<\/span> (<span class=\"hljs-number\">0.00<\/span> sec)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Sixth, insert a new row into the <code>MERGE<\/code> table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-11\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span> t(<span class=\"hljs-keyword\">name<\/span>) <span class=\"hljs-keyword\">VALUES<\/span>(<span class=\"hljs-string\">\"Peter\"<\/span>);<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-11\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The storage engine inserts the row into the t2 table because we set the <code>INSERT_METHOD<\/code> to <code>LAST<\/code> in the <code>CREATE<\/code> <code>TABLE<\/code> statement.<\/p>\n\n\n\n<p>Seventh, query data from the t2 table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-12\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">SELECT<\/span> * <span class=\"hljs-keyword\">FROM<\/span> t2;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-12\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-13\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\">+<span class=\"hljs-comment\">----+-------+<\/span>\n| id | name  |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n|  1 | Bob   |\n|  2 | Alice |\n|  3 | Peter |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n3 rows in <span class=\"hljs-keyword\">set<\/span> (<span class=\"hljs-number\">0.00<\/span> sec)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-13\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Eighth, delete a row from the <code>MERGE<\/code> table with id of 2:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-14\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">DELETE<\/span> <span class=\"hljs-keyword\">FROM<\/span> t <span class=\"hljs-keyword\">WHERE<\/span> <span class=\"hljs-keyword\">id<\/span> = <span class=\"hljs-number\">2<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-14\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The storage engine deletes rows from the table t1 first. If you query data from the t1 table, you&#8217;ll see that the row with id 2 is deleted:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-15\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">SELECT<\/span> * <span class=\"hljs-keyword\">FROM<\/span> t1;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-15\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-16\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\">+<span class=\"hljs-comment\">----+------+<\/span>\n| id | name |\n+<span class=\"hljs-comment\">----+------+<\/span>\n|  1 | John |\n+<span class=\"hljs-comment\">----+------+<\/span>\n1 row in <span class=\"hljs-keyword\">set<\/span> (<span class=\"hljs-number\">0.00<\/span> sec)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-16\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>If you execute the <code>DELETE<\/code> statement that deletes the row with id 2, the storage engine will delete the row in the t2 table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-17\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">DELETE<\/span> <span class=\"hljs-keyword\">FROM<\/span> t <span class=\"hljs-keyword\">WHERE<\/span> <span class=\"hljs-keyword\">id<\/span> = <span class=\"hljs-number\">2<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-17\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Ninth, query data from the t2 table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-18\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\"><span class=\"hljs-keyword\">SELECT<\/span> * <span class=\"hljs-keyword\">FROM<\/span> t2;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-18\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-19\" data-shcb-language-name=\"SQL (Structured Query Language)\" data-shcb-language-slug=\"sql\"><span><code class=\"hljs language-sql\">+<span class=\"hljs-comment\">----+-------+<\/span>\n| id | name  |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n|  1 | Bob   |\n|  3 | Peter |\n+<span class=\"hljs-comment\">----+-------+<\/span>\n2 rows in <span class=\"hljs-keyword\">set<\/span> (<span class=\"hljs-number\">0.00<\/span> sec)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-19\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">SQL (Structured Query Language)<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">sql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use the <code>MERGE<\/code> storage engine to create a <code>MERGE<\/code> table which is a collection of identical MyISAM tables that can be used as one.<\/li>\n<\/ul>\n<div class=\"helpful-block-content\" data-title=\"\">\n\t<header>\n\t\t<div class=\"wth-question\">Was this tutorial helpful? <\/div>\n\t\t<div class=\"wth-thumbs\">\n\t\t\t<button\n\t\t\t\tdata-post=\"12299\"\n\t\t\t\tdata-post-url=\"https:\/\/www.mysqltutorial.org\/mysql-administration\/mysql-merge-storage-engine\/\"\n\t\t\t\tdata-post-title=\"MySQL MERGE Storage Engine\"\n\t\t\t\tdata-response=\"1\"\n\t\t\t\tclass=\"wth-btn-rounded wth-yes-btn\"\n\t\t\t>\n\t\t\t\t<svg\n\t\t\t\t\txmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n\t\t\t\t\tviewBox=\"0 0 24 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