SQL comment, operator, and wildcard characters

An annotation is an explanation or description of the code;

Operators are important components of the Transact-SQL language, and common operators include arithmetic operators, assignment operators, comparison operators, logical operators, and so on.

Wildcard characters are%, _ (underscore), [], [^].

Annotation characters

In Transact-SQL, you can use two types of comment characters:

• An ANSI standard annotation (--) for single-line comments, such as those added by the following SQL statement

 Use -- Open Data Table

The same program annotation symbol as the C language, i.e. "/*", "*/"

The shortcut key to annotate the selected row at once is CTRL + Shift +c; the shortcut key for canceling multiple lines of comment at once is CTRL + Shift +r.

Comparison operators

>,<,=,>=,<=,<>.

The result of the comparison operator is a Boolean data type with True,false and UNKNOW3 values.

logical operators

Logical operators, like comparison operators, return Boolean data types with a value of true or False

Operators are:all,and,any,between,exists,in,like,not,or,some

Bitwise operators

The operand of a bitwise operator can be an integer type or a binary data type

Operator:&,|,^ (bitwise mutex), ~

Join operators

+

Wildcard characters

Matches any single character in the specified range or within the set specified by the square brackets.

Wildcard	Description	Example
%	Any character that contains 0 or more characters	"loving%" can be said: "Loving", "Loving You", "Loving?" ”
_ (Underline)	Any single character	"Loving_" can be said: "LOVINGC". followed by only one character
[]	Any single character in the specified range ([a~f]) or collection ([abcdef])	[0~9]123 denotes a character starting with any character between 0~9 and ending with ' 123 '
[^]	Any single character that does not belong to the specified range ([a~f]) or collection ([abcdef])	[^0~5]123 means a character that does not start with any one character between 0~5, but ends with "123"

SQL comment, operator, and wildcard characters