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What is the syntax for adding columns in SQL

Johnathan Smith

Apr 09, 2025 pm 02:51 PM

The syntax for adding columns in SQL is ALTER TABLE table_name ADD column_name data_type [NOT NULL] [DEFAULT default_value]; where table_name is the table name, column_name is the new column name, data_type is the data type, NOT NULL specifies whether null values are allowed, and DEFAULT default_value specifies the default value.

What is the syntax for adding columns in SQL

SQL syntax for adding columns

In SQL, use the ALTER TABLE statement to add a new column to an existing table. The syntax is as follows:

 <code class="sql">ALTER TABLE table_name ADD column_name data_type [NOT NULL] [DEFAULT default_value];</code>

in:

table_name is the table name to add the column.
column_name is the new column name to be added.
data_type is the data type of the new column, such as INT , VARCHAR , DATE , DECIMAL , etc.
NOT NULL specifies whether the column allows null values.
DEFAULT default_value specifies the default value for this column, and NULL if no value is specified.

Example

For example, to add a new column named email to the customers table, you can execute the following statement:

 <code class="sql">ALTER TABLE customers ADD COLUMN email VARCHAR(255) NOT NULL DEFAULT '';</code>

This will add a new column named email to the customers table, with data type VARCHAR(255) , no null values are allowed, and the default value is an empty string.

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