How Do You Check Data Type in SQL?

In SQL, checking the data type of a column or a value is an important task. It helps ensure that the data being stored or queried is of the expected type. There are several ways to check the data type in SQL, depending on the specific database system you are using.

Using the SQL DESCRIBE Statement

The DESCRIBE statement is commonly used in SQL to retrieve information about a table’s structure. It provides details about the columns in a table, including their data types.

To use the DESCRIBE statement, you would typically execute a query like this:

DESCRIBE table_name;

This will display a result set that includes information about each column in the specified table, such as column name, data type, size, and other attributes.

Using the SQL SHOW COLUMNS Statement

In some database systems, such as MySQL, you can use the SHOW COLUMNS statement to check the data type of columns in a table.

To use the SHOW COLUMNS statement, you would typically execute a query like this:

SHOW COLUMNS FROM table_name;

This will display a result set that includes information about each column in the specified table, including its data type.

The SQL DATATYPE() Function (MySQL)

In MySQL specifically, you can use the DATATYPE() function to check the data type of an expression or value. This function returns a string representation of an expression’s data type.

The syntax for using the DATATYPE() function is as follows:

SELECT DATATYPE(expression);

Here, expression can be any valid SQL expression or column name.

Using the SQL DATA_TYPE Column (Information Schema)

The Information Schema is a database schema that stores metadata about database objects. You can query the Information Schema to retrieve information about columns and their data types.

To check the data type of a column using the Information Schema, you would execute a query similar to this:

SELECT COLUMN_NAME, DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'table_name' AND COLUMN_NAME = 'column_name';

This query will return the specified column’s name and data type from the Information Schema.

In conclusion,

Checking the data type in SQL is crucial for maintaining data integrity and ensuring proper query execution. Whether you use statements like DESCRIBE, SHOW COLUMNS, functions like DATATYPE(), or query the Information Schema, understanding the data types of your columns is essential for effective database management.