UPDATE and DELETE Statements

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  the presenter covers the UPDATE and DELETE statements in SQL, which are used to alter and delete data in a relational database table:

  1. UPDATE Statement: The UPDATE statement is used to modify existing data in a table. Its syntax is as follows: 



  4. UPDATE [TableName] SET [ColumnName] = [Value] WHERE [Condition]

      • [TableName]: Identifies the table to be updated.
      • [ColumnName]: Identifies the column whose value is to be changed.
      • [Value]: Specifies the new value to be assigned to the column.
      • WHERE [Condition]: Specifies the condition that determines which rows will be updated.

    2. DELETE Statement: The DELETE statement is used to remove one or more rows from a table. Its syntax is as follows:

  6. DELETE FROM [TableName] WHERE [Condition]
    [TableName]: Identifies the table from which rows will be deleted. WHERE [Condition]: Specifies the condition that determines which rows will be deleted. The presenter emphasizes the importance of the WHERE clause in both statements. Without the WHERE clause, all rows in the table would be affected by the operation, which may not be desired. In the UPDATE statement example provided, only the row with the specified AUTHOR_ID is updated. Similarly, in the DELETE statement example, only the rows with the specified AUTHOR_ID values are deleted. By understanding and utilizing the UPDATE and DELETE statements along with the WHERE clause, users can effectively alter and remove data from relational database tables in SQL.



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