SQLite 运算符

SQLite 运算符是什么?

运算符是一个保留字或字符主要用于在SQLite语句的WHERE子句中执行操作,如比较和算术运算。

运算符用于指定在SQLite语句的条件,并在一份声明中多个条件作为连词。

  • 算术运算符

  • 比较操作符

  • 逻辑运算符

  • 位运算符

SQLite的算术运算符:

假设变量A=10和变量B=20,则:

查看示例

运算符 描述 示例
+ Addition – Adds values on either side of the operator a + b will give 30
Subtraction – Subtracts right hand operand from left hand operand a – b will give -10
* Multiplication – Multiplies values on either side of the operator a * b will give 200
/ Division – Divides left hand operand by right hand operand b / a will give 2
% Modulus – Divides left hand operand by right hand operand and returns remainder b % a will give 0

SQLite比较操作符:

假设变量A=10和变量B=20,则:

查看示例

运算符 描述 例子
== 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 values 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 values 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.

SQLite的逻辑运算符:

这里是SQLite中所有的逻辑运算符的列表。

查看例子

运算符 描述
AND The AND operator allows the existence of multiple conditions in an SQL statement’s WHERE clause.
BETWEEN The BETWEEN operator is used to search for values that are within a set of values, given the minimum value and the maximum value.
EXISTS The EXISTS operator is used to search for the presence of a row in a specified table that meets certain criteria.
IN The IN operator is used to compare a value to a list of literal values that have been specified.
NOT IN The negation of IN operator which is used to compare a value to a list of literal values that have been specified.
LIKE The LIKE operator is used to compare a value to similar values using wildcard operators.
GLOB The GLOB operator is used to compare a value to similar values using wildcard operators. Also, GLOB is case sensitive, unlike LIKE.
NOT The NOT operator reverses the meaning of the logical operator with which it is used. Eg. NOT EXISTS, NOT BETWEEN, NOT IN, etc. This is negate operator.
OR The OR operator is used to combine multiple conditions in an SQL statement’s WHERE clause.
IS NULL The NULL operator is used to compare a value with a NULL value.
IS The IS operator work like =
IS NOT The IS operator work like !=
|| Adds two different strings and make new one.
UNIQUE The UNIQUE operator searches every row of a specified table for uniqueness (no duplicates).

SQLite的位运算符:

位运算符位和执行位位操作。真值表&和 | 如下:

p q p & q p | q
0 0 0 0
0 1 0 1
1 1 1 1
1 0 0 1

假设,如果A= 60;和B=13;现在以二进制格式,他们将作如下:

A = 0011 1100

B = 0000 1101

—————–

A&B = 0000 1100

A|B = 0011 1101

~A  = 1100 0011

下表中列出的位运算符支持SQLite的语言的。假设变量A=60和变量B=13,则:

查看例子

运算符 描述 示例
& Binary AND Operator copies a bit to the result if it exists in both operands. (A & B) will give 12 which is 0000 1100
| Binary OR Operator copies a bit if it exists in either operand. (A | B) will give 61 which is 0011 1101
~ Binary Ones Complement Operator is unary and has the effect of ‘flipping’ bits. (~A ) will give -61 which is 1100 0011 in 2’s complement form due to a signed binary number.
<< Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. A << 2 will give 240 which is 1111 0000
>> Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. A >> 2 will give 15 which is 0000 1111
    原文作者:SQLite教程
    原文地址: https://www.yiibai.com/sqlite/sqlite_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