Knowledge about SQL undo indexes, tables and databases

SQL UndoIndices, tables and databases are very important in php, this article will explain them.

SQL DROP INDEX statement

We can use the DROP INDEX commandto delete the index in the table.

Syntax for Microsoft SQLJet (and Microsoft Access):

DROP INDEX index_name ON table_name

Syntax for MS SQL Server:

DROP INDEX table_name.index_name

For IBM DB2 and Oracle Syntax:

DROP INDEX index_name

For MySQL Syntax:

ALTER TABLE table_name DROP INDEX index_name

SQL DROP TABLE statement

The DROP TABLE statement is used to delete a table (table structure, Attributes and indexes will also be deleted):

DROP TABLE table name

SQL DROP DATABASE statement

The DROP DATABASE statement is used to delete the database:

DROP DATABASE database name

SQL TRUNCATE TABLE statement

If we only need to remove the data in the table, but do not delete the table itself, then what should we do? Woolen cloth?

Please use the TRUNCATE TABLE command (only delete the data in the table):

TRUNCATE TABLE table name

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