Shulou(Shulou.com)05/31 Report--

This article mainly explains "the usage of MySQL cursor syntax". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "the usage of MySQL cursor syntax".

1. Basic grammar:

Sql code

# define cursors

Declare fetchSeqCursor cursor for select seqname, value from sys_sequence

# using cursors

Open fetchSeqCursor

# fetch data

Fetch cursor into _ seqname, _ value

# close cursors

Close fetchSeqCursor

2. Example of single Vernier:

Sql code

# # define the flag for loop judgement

Declare fetchSeqOk boolean

# # define the varient for store the data

Declare _ seqname varchar (50)

Declare _ value bigint (20)

# # define the cursor

Declare fetchSeqCursor cursor for select seqname, value from sys_sequence

# # define the continue handler for not found flag

Declare continue handler for NOT FOUND set fetchSeqOk = true

Set fetchSeqOk = false

Open fetchSeqCursor

FetchSeqLoop:Loop

If fetchSeqOk then

Leave fetchSeqLoop

Else

Fetch cursor into _ seqname, _ value

Select _ seqname, _ value

End if

End Loop

Close fetchSeqCursor

3. Nested cursor loops

Java code

# # define the flag for loop judgement

Declare fetchSeqOk boolean

# # define the varient for store the data

Declare _ seqname varchar (50)

Declare _ value bigint (20)

# # define the cursor

Declare fetchSeqCursor cursor for select seqname, value from sys_sequence

# # define the continue handler for not found flag

Declare continue handler for NOT FOUND set fetchSeqOk = true

Set fetchSeqOk = false

Open fetchSeqCursor

FetchSeqLoop:Loop

If fetchSeqOk then

Leave fetchSeqLoop

Else

Fetch cursor into _ seqname, _ value

# nested cursor loops

Begin

Declare fetchSeqOk boolean default 'inner'

# # define the cursor

Declare cursor2 cursor for select.... From...

# # define the continue handler for not

Declare continue handler for NOT FOUND set fetchSeqOk = true

Set fetchSeqOk = false

Open cursor2

Fetchloop2 loop

If fetchSeqOk then

Else

End if

End loop

Close cursor2

End

# end of nested cursor loop

End if

End Loop

Close fetchSeqCursor

At this point, I believe you have a deeper understanding of "the use of MySQL cursor syntax". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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