How to write update statements in SQL

The UPDATE statement in SQL is used to modify existing records: Syntax: UPDATE table_name SET column1 = new_value1, column2 = new_value2, ... WHERE condition Usage: Specify the table name List the columns to be updated in the SET clause and the new value to be updated. Use the WHERE clause to specify the update conditions (optional)

SQL Update Statement: Syntax and Usage

In SQL, the UPDATE statement is used to modify existing records in the database table.

grammar:

 <code class="sql">UPDATE table_name SET column1 = new_value1, column2 = new_value2, ... WHERE condition</code>

explain:

• table_name: The table name to be updated.
• SET: Specifies the column to be updated and its new value.
• condition: An optional condition that specifies the specific record to be updated.

usage:

1. Determine the table to be updated: Specify the name of the table to be updated.
2. Specify the columns to be updated: List the columns to be updated in the SET clause and assign them a new value.
3. Add condition (optional): Use the WHERE clause to specify a filter condition that determines the specific record to be updated. If no conditions are present, all records in the table will be updated.

Example:

To update name column in the students table as "John" with id column as 1, you can use the following statement:

 <code class="sql">UPDATE students SET name = 'John' WHERE id = 1;</code>

To update all records age greater than 30 in the users table, add 1 to its age column, you can use the following statement:

 <code class="sql">UPDATE users SET age = age 1 WHERE age > 30;</code>

Notes:

• Make sure the column name specified to be updated is spelled correctly.
• Ensure that the new value is compatible with the column's data type.
• If no criteria are specified, all records in the table are updated.
• Always perform data backup before modifying sensitive data.

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