MySQL Learning note ten (MySQL operator)

The operator provided by MySQL contains arithmetic operators, comparison operators, logical operators, and bitwise operators.

Arithmetic operators
Includes: +-*/%
1. Get the results after various arithmetic operations
Select
6+4 ' addition ',
6-4 ' subtraction ',
6*4 ' multiplication ',
6/4 ' Division ',
6 Div 4 ' division ',
6%4 ' Find the mold ',
6 mod 4 ' modulo ';
+--+--+--+--–+--+--+--+
| Addition | Subtraction | multiplication | Division | Division | Die-Finding | Die-Finding |
+--+--+--+--–+--+--+--+
| 10 | 2 | 24 | 1.5000 | 1 | 2 | 2 |
+--+--+--+--–+--+--+--+
2, in addition to manipulating values, you can also manipulate the fields in the table
Select Ename ' employee ', Sale ' monthly salary ', sale*12 ' annual salary ' from T_employee;
3, in addition to operators (/and DIV) and modulo operators (% and MoD), if the divisor of 0 will be an illegal operation, the return result is null
Select 6/0 ' Division ',
6 Div 0 ' division ',
6%0 ' Die ',
6MOD0 ' seeking mode ';
+--+--+--+--+
| Division | Division | Die-Finding | Die-Finding |
+--+--+--+--+
| NULL | NULL | NULL | NULL |
+--+--+--+--+
Comparison operators
Comparison operators contain common comparison operators and implement special function comparison operators
Common comparison operators

< = (<=>)! = (<>) >= <=
Attention:
1, = and <=>
* All can be judged by the value, whether the string and the expression are equal, and the equivalent returns 1. otherwise returns 0;
Select
1=1 ' numerical comparison ',
' Cjgong ' = ' cjgong ' string comparison ',
1+2=3+3 ' expression comparison ',
1<=>1 ' numerical comparison ',
' Cjgong ' = ' cjgong ' string comparison ',
1+2<=>3+3 ' expression comparison ';
+ ———-+ —————————— –+ ———— + ———-+ —————————— –+ ———— +
| Numerical comparison | ' Cjgong ' = ' cjgong ' string comparison ' | Expression Comparison | Numerical comparison | ' Cjgong ' = ' cjgong ' string comparison ' | Expression Comparison |
+ ———-+ —————————— –+ ———— + ———-+ —————————— –+ ———— +
| 1 | 0 | 0 | 1 | 0 | 0 |
+ ———-+ —————————— –+ ———— + ———-+ —————————— –+ ———— +
* When comparing strings for equality, = cannot manipulate null, while the latter can.
mysql> Select Null<=>null ' <=> symbol effect ', null=null ' = symbol effect ';
+ ————-+ ——— –+
| <=> Symbolic Effects | = Symbol Effect |
+ ————-+ ——— –+
| 1 | NULL |
+ ————-+ ——— –+
2,! = and <> These two comparison operators cannot manipulate null
3. >,>=,<,<= comparison operators also cannot manipulate null
Special operators
Between...and
Is null
Inch
Like
RegExp: Regular expression matching
Regular expressions
The mode characters supported by MySQL are as follows:
^ Start
$ end
. Any one character
Any one of the characters in the [character set] Collection
Any character outside the collection of [^ charset]
STR1|STR2|STR3 matches any one of three strings
* Match characters, 0 or 1
+ Match character, contains 1
string {n} string appears N times
String (m,n) string appears at least M times, up to N times
logical operators
and (&&)
OR (| |)
Not (!)
Xor
Bitwise operators
& | ~ ^ << >>
BIN () binary representation
Select 4&5,bin (4&5) ' binary ', 4&5&6,bin (4&5&6) ' binary ';
+-–+--–+ ——-+--–+
| 4&5 | binary | 4&5&6 | binary |
+-–+--–+ ——-+--–+
| 4 | 100 | 4 | 100 |
+-–+--–+ ——-+--–+

MySQL Learning note ten (MySQL operator)