发布于 2015-07-25 11:49:19 | 100 次阅读 | 评论: 0 | 来源: 网络整理
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. |
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