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Db2 ALTER TABLE ALTER COLUMN allows you to modify the definitions of the existing columns in a table. The following illustrates the syntax of the ALTER TABLE ALTER COLUMN statement: ALTER TABLE table_name. ALTER COLUMN column_name. modification_type; Code language: SQL (Structured Query Language) (sql) In this syntax:
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The ALTER TABLE statement alters the definition of a table. Invocation. This statement can be embedded in an application program or issued by using dynamic SQL statements. It is an executable statement that can be dynamically prepared only if DYNAMICRULES run behavior is in effect for the package (SQLSTATE 42509). Authorization
Alter table SET DATA TYPE support. The ALTER COLUMN SET DATA TYPE option on the ALTER TABLE statement supports all compatible types. Altering the column data type can cause data loss.
ALTER TABLE ChildTableName DROP FOREIGN KEY `fk_table`; ALTER TABLE ChildTableName ADD CONSTRAINT `fk_t1_t2_tt` FOREIGN KEY (`parentTable`) REFERENCES parentTable (`columnName`) ON DELETE CASCADE ON UPDATE CASCADE;
To change the data type of a column in a table, use the following syntax: SQL Server / MS Access: ALTER TABLE table_name. ALTER COLUMN column_name datatype; My SQL / Oracle (prior version 10G): ALTER TABLE table_name. MODIFY COLUMN column_name datatype; Oracle 10G and later: ALTER TABLE table_name.
First, specify the name of the table to which you want to add the new column in the ALTER TABLE clause. Second, specify the new column including name, data type, and column constraint in the ADD COLUMN clause.
In this tutorial, you'll learn how to drop one or more columns in a table by using the Db2 ALTER TABLE DROP COLUMN statement.
