SQLite 比较操作符

假设变量a=10和变量b=20,那么比较运算符将使用SQLite如下:

运算符 描述 实例
== Checks if the values of two operands are equal or not, if yes then condition becomes true. (a == b) is not true.
= Checks if the values of two operands are equal or not, if yes then condition becomes true. (a = b) is not true.
!= Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. (a != b) is true.
<> Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. (a <> b) is true.
> Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true. (a > b) is not true.
< Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true. (a < b) is true.
>= Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true. (a >= b) is not true.
<= Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true. (a <= b) is true.
!< Checks if the value of left operand is not less than the value of right operand, if yes then condition becomes true. (a !< b) is false.
!> Checks if the value of left operand is not greater than the value of right operand, if yes then condition becomes true. (a !> b) is true.

示例

COMPANY 表有以下记录:

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0

下面的例子将展示各种SQLite的比较操作符的用法。

在这里,我们使用WHERE子句,这将是在一个单独的章节解释,但现在可以明白,WHERE子句用来做SELECT一个条件语句。

下面的SELECT语句列表的SALARY大于50,000.00下来的所有记录:

sqlite> SELECT * FROM COMPANY WHERE SALARY > 50000;
ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0

下面的SELECT语句列出了所有的记录,SALARY 等于20,000.00:

sqlite>  SELECT * FROM COMPANY WHERE SALARY = 20000;
ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
3           Teddy       23          Norway      20000.0

下面的SELECT语句列出了所有的记录,SALARY 不等于20,000.00:

sqlite>  SELECT * FROM COMPANY WHERE SALARY != 20000;
ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
2           Allen       25          Texas       15000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0

下面的SELECT语句列出了所有的记录,SALARY 不等于20,000.00:

sqlite> SELECT * FROM COMPANY WHERE SALARY <> 20000;
ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
2           Allen       25          Texas       15000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0

下面的SELECT语句列表的SALARY 大于或等于65,000.00下来的所有记录:

sqlite> SELECT * FROM COMPANY WHERE SALARY >= 65000;
ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0

        原文作者:SQLite教程
        原文地址: https://www.yiibai.com/sqlite/sqlite_comparison_operators.html
        本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
    点赞

    发表评论

    电子邮件地址不会被公开。 必填项已用*标注