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Transact-SQL User's Guide |
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| Chapter 13 Using Batches and Control-of-Flow Language |
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| Using control-of-flow language |
Use control-of-flow language with interactive statements, in batches, and in stored procedures. Table 13-1lists the control-of-flow and related keywords and their functions.
Keyword | Function |
if | Defines conditional execution. |
...else | Defines alternate execution when the if condition is false. |
case | Defines conditional expressions using when...then statements instead of if...else. |
begin | Beginning of a statement block. |
...end | End of a statement block. |
while | Repeat performance of statements while condition is true. |
break | Exit from the end of the next outermost while loop. |
...continue | Restart while loop. |
declare | Declare local variables. |
goto label | Go to label:, a position in a statement block. |
return | Exit unconditionally. |
waitfor | Set delay for command execution. |
Print a user-defined message or local variable on user's screen. | |
raiserror | Print a user-defined message or local variable on user's screen and set a system flag in the global variable @@error. |
/* comment */or --comment | Insert a comment anywhere in a Transact-SQL statement. |
| if...else |
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| case expression |
| Using case expression for alternative representation |
| case and division by zero |
| Using rand() functions in case expressions |
| case expression results |
| case expression requires at least one non-null result |
| case |
| case and value comparisons |
| coalesce |
| nullif |
| begin...end |
| while and break...continue |
| declare and local variables |
| goto |
| return |
| raiserror |
| Creating messages for print and raiserror |
| waitfor |
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| Comments |
| Slash-asterisk style comments |
| Double-hyphen style comments |
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