SELECT语句用于从单个或多个表中检索记录。
语法:
SELECT expressions FROM tables [WHERE conditions];
SELECT语句可以与UNION语句,ORDER BY子句,LIMIT子句,WHERE子句,GROUP BY子句,HAVING子句等一起使用。
SELECT [ ALL | DISTINCT ] expressions FROM tables [WHERE conditions] [GROUP BY expressions] [HAVING condition] [ORDER BY expression [ ASC | DESC ]];
示例: 无涯教程有一个"Students"表,有一些数据。所以从"Students"中检索所有记录。
SELECT * FROM Students;
输出:
您可以使用SELECT语句从表中检索各个列。它有助于您仅检索所需的那些列。
SELECT student_id, student_name, student_address FROM Students WHERE student_id < 5 ORDER BY student_id ASC;
输出:
在这里,无涯教程从" students"表中选择" student_id"小于5的" student_id"," student_name"," student_address",并根据" student_id"以升序对记录进行排序。
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