SQL ALTER TABLE

Once a table is created in the database, there are many occasions where one may wish to change the structure of the table. In general, the SQL syntax for ALTER TABLE is,

[alter specification] is dependent on the type of alteration we wish to perform. We list a number of common changes below:

• Add Column
• Change Column
• Modify Column
• Rename Column
• Drop Column
• Add Index
• Drop Index
• Add Constraint
• Drop Constraint

For all cases except Change Column, examples are provided for MySQL, Oracle, and SQL Server. SparkSQL and Hive SQL (HiveQL) only support Add Column and Change Column with ALTER TABLE.