The Db2 basics section teaches you everything you need to know to interact with Db2 database effectively.<\/p>\n\n\n\n
This section shows you how to query data from the Db2 database. We will start with a simple SELECT statement that allows you to query data from columns of a table.<\/p>\n\n\n\n
This section describes how to use the set operators including union, intersect, and except to combine two or more result sets from subselects.<\/p>\n\n\n\n
UNION ALL<\/code> operator retains the duplicate rows in the result.<\/li>- INTERSECT<\/a> \u2013 combine two or more result sets and return the rows that exist in all the result sets.<\/li>
- EXCEPT<\/a> \u2013 return the result of the first subselect minus any matching rows from the result set of the second subselect.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 10. Common Table Expression (CTE)<\/h2>\n\n\n\n- CTE<\/a> \u2013 use common table expressions to simplify complex queries.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 11. Modifying Data<\/h2>\n\n\n\n
In this section, you will learn how to insert, update, and delete data from a table.<\/p>\n\n\n\n
- INSERT<\/a> \u2013 insert a row into a table<\/li>
- INSERT multiple rows<\/a> \u2013 insert multiple rows into a table.<\/li>
- INSERT INTO SELECT<\/a> \u2013 insert data returned by a SELECT statement into a table.<\/li>
- UPDATE<\/a> \u2013 modify the existing data in a table.<\/li>
- DELETE<\/a> \u2013 delete one or more rows from a table.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 12. Data Definition Language<\/h2>\n\n\n\n
This section shows you how to manage the most important database objects including databases and tables.<\/p>\n\n\n\n
- CREATE TABLE<\/a> \u2013 show you how to create a new table in the database.<\/li>
- Identity column<\/a> \u2013 learn how to define an identity column for a table.<\/li>
- ADD COLUMN<\/a> \u2013 describe how to add one or more columns to a table<\/li>
- ALTER COLUMN<\/a> \u2013 show you how to modify definitions of existing columns in a table.<\/li>
- DROP COLUMN<\/a> \u2013 walk you through the process of dropping one or more columns in a table.<\/li>
- DROP TABLE<\/a> \u2013 show you how to delete table objects permanently from the database.<\/li>
- TRUNCATE TABLE<\/a> \u2013 give you a more efficient way to delete all data from a big table.<\/li>
- Rename a table<\/a> \u2013 learn how to change the name of an existing table to the new one.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 13. Db2 Data Types<\/h2>\n\n\n\n- Integers<\/a> \u2013 learn various integer types in Db2 including BIGINT, INT, and SMALLINT.<\/li>
- Decimal<\/a> \u2013 introduce you to decimal type and show you how to use it to store decimal numbers in tables.<\/li>
- CHAR<\/a> \u2013 learn how to store fixed-length character strings in the database.<\/li>
- VARCHAR<\/a> \u2013 store varying character strings in the database.<\/li>
- DATE<\/a> \u2013 discuss the
DATE<\/code> data type and how to store the dates in the database.<\/li>- TIME<\/a> \u2013 learn about the
TIME<\/code> data type and how to work with time data.<\/li>- TIMESTAMP<\/a> \u2013 introduce you to timestamp data type and show you how to store the timestamp in the database.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 14. Constraints<\/h2>\n\n\n\n- Primary key<\/a> \u2013 learn about the primary key and how to use the primary key constraint to define the primary key for a table.<\/li>
- Foreign key<\/a> \u2013 enforce referential integrity between tables by using foreign key constraints.<\/li>
- DEFAULT<\/a> – specify a default value for a column to be inserted when the application doesn’t supply the value.<\/li>
- NOT NULL<\/a> \u2013 prevent NULL from inserting or update to a column.<\/li>
- UNIQUE<\/a> \u2013 enforce the data in a column or group of columns is unique in all rows of a table.<\/li>
- CHECK<\/a> \u2013 place a condition on the values which are being inserted or updated into a table.<\/li><\/ul>\n<\/div><\/div>\n\n\n\n\n
Section 15. Useful Expressions & Functions<\/h2>\n\n\n\n- CASE<\/a> \u2013 use simple and searched CASE expressions to add if-else logic to queries.<\/li>
- COALESCE<\/a> \u2013 learn how to handle NULL values effectively.<\/li>
- CAST<\/a> – convert a value of one type to another.<\/li><\/ul>\n<\/div><\/div>\n\n\t
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