SQL 句法基础知识数据库(database) – 表格(table) – 记录(record)& 列(column) 数据库操作通过SQL statements实现 SQL 语句(statements)不区分大小写 某些数据库会要求语句最后添加分号(;),所以在所有语句最后添加分号才是标准写法 一些重要的SQL语句:SELECT - extracts data from a databaseUPDATE - updates data in a databaseDELETE - deletes data from a databaseINSERT INTO - inserts new data into a databaseCREATE DATABASE - creates a new databaseALTER DATABASE - modifies a databaseCREATE TABLE - creates a new tableALTER TABLE - modifies a tableDROP TABLE - deletes a tableCREATE INDEX - creates an index (search key)DROP INDEX - deletes an indexSQL语句SELECTSELECT DISTINCTWHERE对于字符串,SQL要求使用单引号( ’ ’ ),大多数数据库也支持双引号where中的操作符:OperatorDescription=Equal<>Not equal. Note: In some versions of SQL this operator may be written as !=>Greater than
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