What is alter command in sql
The SQL ALTER TABLE command is used to add, delete or modify columns in an existing table. You should also use the ALTER TABLE command to add and drop various constraints on an existing table. SQL ALTER TABLE Statement The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table. ALTER TABLE - ADD Column.
Modifies a table definition by altering, adding, or dropping columns and constraints. Use the following links to take you directly to the appropriate syntax block for your table types and to the appropriate syntax examples:. If the table isn't in the current database or contained by the schema owned by the current user, you must explicitly specify the database and schema.
The data type of textntextand image columns can be changed only in the following ways:. Some data type changes may cause a change in the data. For example, changing a nchar or nvarchar column, to char or varcharmight cause the conversion of extended characters. Reducing the precision or scale of download how the grinch stole christmas cartoon column can cause data truncation.
