When a partitioning operation cascades to reference-partitioned child tables, privileges are not required on the reference-partitioned child tables. You must also have space quota in the tablespace in which space is to be acquired in order to use the add_table_partition, modify_table_partition, move_table_partition, and split_table_partition clauses. In this tutorial, you have learned how to use the SQL Server ALTER TABLE ALTER COLUMN to modify some properties of an existing column.The table must be in your own schema, or you must have ALTER object privilege on the table, or you must have ALTER ANY TABLE system privilege.Īdditional Prerequisites for Partitioning Operations If you are not the owner of the table, then you need the DROP ANY TABLE privilege in order to use the drop_table_partition or truncate_table_partition clause. If you want to add the NOT NULL constraint to the column c, you must update NULL to non-null first for example: UPDATE t3Īnd then add the NOT NULL constraint: ALTER TABLE t3 ALTER COLUMN c VARCHAR ( 20) NOT NULL The following statement inserts some rows into the table: INSERT INTO t3 The following statement creates a new table with a nullable column: CREATE TABLE t3 (c VARCHAR( 50)) Code language: SQL (Structured Query Language) ( sql ) Add a NOT NULL constraint to a nullable column SQL Server issued the following error: String or binary data would be truncated. If the conversion fails, SQL Server terminates the statement and issues an error message.įor example, if you decrease the size of column c to 5 characters: ALTER TABLE t2 ALTER COLUMN c VARCHAR ( 5) Code language: SQL (Structured Query Language) ( sql ) However, when you decrease the size of the column, SQL Server checks the existing data to see if it can convert data based on the new size. You can increase the size of the column as follows: ALTER TABLE t2 ALTER COLUMN c VARCHAR ( 50) Let’s insert some sample data into the t2 table: INSERT INTO t2 The following statement creates a new table with one column whose data type is VARCHAR(10): CREATE TABLE t2 (c VARCHAR( 10))

Code language: SQL (Structured Query Language) ( sql ) Change the size of a column SQL Server issued the following error: Conversion failed when converting the varchar value to data type int. VALUES ( language: SQL (Structured Query Language) ( sql )įourth, modify the data type of the column from VARCHAR back to INT: ALTER TABLE t1 ALTER COLUMN c INT

Third, insert a new row with a character string data: INSERT INTO t1 Second, modify the data type of the column from INT to VARCHAR: ALTER TABLE t1 ALTER COLUMN c VARCHAR ( 2) Second, insert some rows into the table: INSERT INTO t1 The new data type must be compatible with the old one, otherwise, you will get a conversion error in case the column has data and it fails to convert.įirst, create a new table with one column whose data type is INT: CREATE TABLE t1 (c INT) To modify the data type of a column, you use the following statement: ALTER TABLE table_nameĪLTER COLUMN column_name new_data_type( size) Ĭode language: SQL (Structured Query Language) ( sql ) SQL Server allows you to perform the following changes to an existing column of a table: Summary: in this tutorial, you will learn how to use the SQL Server ALTER TABLE ALTER COLUMN statement to modify a column of a table.

Alter table rename column