Variable:
the SQL language, like other programming languages, has control statements such as variables, branches, loops, and so on.
In SQL language, variables are divided into local variables and global variables, and global variables are called system variables.
Local variables:
Using the declare keyword to declare a variable, the syntax is simple:declare @< variable name > < variable type >
You can assign values to variables using the set keyword, and you can assign only one value to a variable at a time using the Set keyword.
We can also assign a value to this variable in a query statement.
Example:
Global variables: Also called system variables.
Examples of several system variables that are commonly used:
Variable Small exercise:
Exercises for defining variables:
You need to print a single quotation mark in a printed string: Double-two single quotes.
Operator:
Practice:
Operator Precedence:
If...else ... statement:
Example:
Practice:
While statement:
Example:
W hile If nesting example:
Example of break in while :
Example of parsing each step of a loop print:
Case ... when ... Example:
SQL variables, operators, if, while