1. What is the SQL statement
Structed Query Language SQL is an acronym, that Structured Query Language. SQL is a standard language for database manipulation and retrieval, standard SQL statements can operate any relational database.
2, there are standard SQL statements are the following classification
1 "query: select mainly by keyword query SQL statement is the most complex, feature-rich statement.
2 "DML (Data Manipulation Language, Data Manipulation Language) statements: keywords have insert, update, delete.
3 "DDL (Data Definition Language, Data Definition Language) statements: keywords have create, alter, drop, truncate.
4 "DCL (Data Control Language, Data Control Language) statements: keyword has grant, revoke.
5 "Transaction Control statements: keyword has commit, rollback, savepoint.
Keywords SQL statements are not case sensitive, that is, select and SELECT, or selEct are equivalent, as long as the keyword.
Another point: truncate DDL is a special keyword, which is equivalent to delete the specified data table, and then rebuild the data table
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