Category Archives: sql

SQL – ALTER TABLE Table of content SQL − ALTER TABLE Statement The SQL ALTER TABLE command is a part of Data Definition Language (DDL) and modifies the structure of a table. The ALTER TABLE command can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or […]

SQL – Constraints Table of content SQL Constraints SQL Constraints are the rules applied to a data columns or the complete table to limit the type of data that can go into a table. When you try to perform any INSERT, UPDATE, or DELETE operation on the table, RDBMS will check whether that data violates […]

SQL – Data Types Table of content What are SQL Data types? An SQL data type refers to the type of data which can be stored in a column of a database table. In a column, the user can store numeric, string, binary, etc by defining data types. For example integer data, character data, monetary […]