Renaming Tables and Columns
Modifying the names of existing tables and columns in an SQL database management system is an essential and very useful task, where database users need to manually update the database structure to reflect organizational or business needs, industry data modelling, or naming conventions. Replacing database table column names involves replacing or modifying the name of an existing table or column without directly impacting the table record data stored in the existing table.
The rename operation on table columns in a database table is performed by applying the ALTER TABLE command statement, but the syntax and application method may differ slightly depending on the database system, such as MySQL, PostgreSQL, and SQL Server software.
Renaming a Table in an SQL Database.
To rename an existing table in a database table, the database user needs to apply the ALTER TABLE command statement, which is used with a command to rename an existing database table. The syntax for applying the rename table command may vary or have multiple syntaxes depending on the different database software.
Syntax for Renaming a Table in a Database Table.
In MySQL and MariaDB database software.
ALTER TABLE old_table_name
RENAME TO new_table_name;
In PostgreSQL database software.
ALTER TABLE old_table_name
RENAME TO new_table_name;
In SQL Server database software.
EXEC sp_rename ‘old_table_name’, ‘new_table_name’;
Example of Renaming a Table in MySQL/PostgreSQL.
ALTER TABLE employe
RENAME TO team;
In this example.
- Here, in this example, the database table name ’employe’ has been renamed to ‘team’.
Example of renaming a table in SQL Server software.
EXEC sp_rename ’employe’, ‘team’;
In this example.
- In this example, the employee table in SQL Server has been renamed to team using the sp_rename stored procedure command method.
Renaming a Column in a Database Table.
To rename a database table column, database users also use the ALTER TABLE command statement, although the syntax for renaming a column differs in different DBMS software.
Syntax for renaming a column in a database table.
In MySQL database software.
MySQL database software does not provide users with a direct RENAME COLUMN syntax feature. Instead, the database uses the CHANGE COLUMN clause to rename a table column and redefine the column’s data type, even if the database table column data type remains unchanged.
ALTER TABLE table_name
CHANGE COLUMN old_column_name new_column_name column_definition;
Here, the table column_definition can include the column data type and any constraints associated with the column.
In PostgreSQL database software.
ALTER TABLE table_name
RENAME COLUMN old_column_name TO new_column_name;
In SQL Server database software.
EXEC sp_rename ‘table_name.old_column_name’, ‘new_column_name’, ‘COLUMN’;
Example of renaming a table column in MySQL database software.
ALTER TABLE employe
CHANGE COLUMN first_name f_name VARCHAR(130);
In this example.
- Here, in this example, the table column first_name has been replaced with f_name, and its data type is VARCHAR(130) character length.
Example of renaming a column in a table in PostgreSQL database software.
ALTER TABLE employe
RENAME COLUMN first_name TO f_name;
In this example.
- Here, in this example, the column first_name has been replaced with f_name in PostgreSQL database software.
Example of renaming a column in SQL Server database software.
EXEC sp_rename ’employe.first_name’, ‘f_name’, ‘COLUMN’;
In this example.
- In this example, the sp_rename stored procedure method in SQL Server is used to rename the column first_name to f_name.
Key considerations when renaming database tables and columns.
Impact on dependent objects.
- Views – Any table views in the database that reference the old table or column names will need to be updated to reflect the new names.
- Stored Procedures and Functions – If stored procedures or functions in the database use the old table or column names, the database user will need to modify them accordingly.
- Indexes and Triggers – When performing a database table rename operation, ensure that table indexes, triggers, and foreign keys that reference the old table name are updated or modified accordingly.
Database Table Constraints and Foreign Keys.
If a renamed table column in a database table is part of a foreign key constraint or has a unique constraint, the user must ensure that the related constraints are also updated to avoid any errors.
Application Code for the Database.
If the database user’s application code, such as queries, APIs, or business logic, uses the old table or column name, the database user must update the application code/APIs to use the new name.
Data Integrity in Database Tables.
Renaming a database table or column does not impact the stored table data. The table data remains secure as long as the table data structure, data types, and constraints are not modified.
Example of renaming a database table and column.
Step 1: Rename a database table.
Here, we rename the ’employe’ table to ‘team’ in MySQL/PostgreSQL database management software.
ALTER TABLE employe
RENAME TO team;
Step 2: Rename a column in MySQL database management software.
Rename the ‘first_name’ table column to ‘f_name’ in MySQL database software.
ALTER TABLE staff
CHANGE COLUMN first_name f_name VARCHAR(130);
Step 3: Rename a column in PostgreSQL database management software.
Rename the ‘first_name’ table column to ‘f_name’ in PostgreSQL database management software.
ALTER TABLE team
RENAME COLUMN first_name TO f_name;
Step 4: Rename a column in SQL Server database management software.
Rename the ‘first_name’ column to ‘f_name’ in SQL Server database software.
EXEC sp_rename ‘team.first_name’, ‘f_name’, ‘COLUMN’;
Conclusion of Renaming SQL Database Tables and Columns.
- In SQL database management systems, renaming tables and columns is done by applying the ALTER TABLE command statement. The exact command syntax depends on the specific database system software being used by the database user.
- To rename a database table, use ALTER TABLE … RENAME TO in MySQL/PostgreSQL or EXEC sp_rename in SQL Server.
- To rename a column in a database table, use ALTER TABLE … CHANGE COLUMN in MySQL, ALTER TABLE … RENAME COLUMN in PostgreSQL, or EXEC sp_rename in SQL Server database software.
