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。
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算术运算符
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比较操作符
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逻辑运算符
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位运算符
SQLite的算术运算符：
假设变量A=10和变量B=20，则：
| 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：
| 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。
| 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：
| 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 |
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欢迎任何形式的转载，但请务必注明出处，尊重他人劳动共创优秀实例教程
转载请注明：文章转载自：代码驿站 [http:/www.codeinn.net]
本文标题：SQLite 运算符
本文地址：http://www.codeinn.net/sqlite/174.html
