SQLite 運算符

SQLite 運算符是什麼？

運算符是一個保留字或字符主要用於在SQLite語句的WHERE子句中執行操作，如比較和算術運算。

運算符用於指定在SQLite語句的條件，並在一份聲明中多個條件作為連詞。

假設變量A=10和變量B=20，則：

運算符	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

假設變量A=10和變量B=20，則：

運算符	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.

這裡是SQLite中所有的邏輯運算符的列表。

運算符	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).

位運算符位和執行位位操作。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

假設，如果A= 60;和B=13;現在以二進製格式，他們將作如下：

A = 0011 1100

B = 0000 1101

-----------------

A&B = 0000 1100

A|B = 0011 1101

~A = 1100 0011

下表中列出的位運算符支持SQLite的語言的。假設變量A=60和變量B=13，則：

運算符	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