In database scripts, begin and end are a pair of strange words. Without them, some code looks confused, adding them, and the structure of the code is instantly clear.
Indeed, beginning and end are the starting and ending flags for code statements, making the scripting logic clear and easy to read.
Begin and end are mainly used in the following places:
1. If, else, else if, while, etc statements
If, else, else if, while and other statements to own a row, the execution statement must not immediately follow, no matter how many execution statements have to add the statement block flag begin...end.
The Begin and end in the script file should be exclusive and in the same starting column, aligned to the left of the statement that references them. The code block within the Begin...end uses indents, typically indented to 4 spaces.
Positive example:
if (@varible1 < @varible2)
Begin
[EXECUTE statement]
End
Counter Example 1:
if (@varible1 < @varible2)
[EXECUTE statement 1]
[EXECUTE Statement 2]
In inverse 1, because of the lack of begin and end, the "Attribution question" of "EXECUTE statement 1" and "EXECUTE Statement 2" is confusing, and it is easy to make the logic of the code wrong.
Counter Example 2:
if (@varible1 < @varible2)
Begin
[EXECUTE statement]
End
In anti-Example 2, begin and end are not in the same starting column, nor are left-aligned with the statement that references them. So the code looks messy.
Counter Example 3:
if (@varible1 < @varible2) begin
[EXECUTE statement]
End
In anti-Example 3, it is also not normal for the begin and if statements to be in the same line of code.
2. When creating stored procedures (functions, triggers, etc.)
When a stored procedure (function, trigger, etc.) is created, the number of rows in the execution statement content portion of the stored procedure (function, trigger, and so on) must begin with begin, end, and the name of the stored procedure (function, trigger, and so on).
Example 1 (creating stored procedures based on Sybase database):
if exists (select 1 from sysobjects where name = ' pr_example ')
begin
drop procedure pr_example
end
go
create procedure pr_example
@name varchar ()- -name
@age int --age
as DECLARE @begintime varchar, --Start time
@endtime varchar ()-- end time
begin
[ Execute statement part] End go
print ' CREATE PROCEDURE pr_example OK '
go
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Example 2 (creating a stored procedure based on an Oracle database):
Create or Replace procedure Pr_example
(
v_name in Varchar2, --name
v_age out int --age
)
As
begintime varchar2 (a); --Start time
endtime varchar2; End time
begin
[EXECUTE statement part]
;
/
Prompt ' CREATE procedure pr_example OK ';
In addition, when you create stored procedures (functions, triggers, and so on), each parameter must be on a single line, with no line wrapping or multiple arguments allowed. The comment for this parameter is either on the same line as the parameter or on a separate line, and does not allow wrapping on the parameter line. The following code is not canonical:
Example 3 (creating a stored procedure based on an Oracle database):
Create or Replace procedure Pr_example
(
v_name in Varchar2, --name
v_age out int
--age
)
As
begintime varchar2 (a); --Start time-
-end time
endtime
varchar2;
Begin
[EXECUTE statement part] End
;
/
Prompt ' CREATE procedure pr_example OK ';
In the actual software project, the proper use of begin and end can make the logic of the code clear and readable. This is conducive to the improvement of work efficiency.