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Topic: Operation cannot be performed on an active dataset (Read 2896 times)
martinrame
Full Member
Posts: 119
Operation cannot be performed on an active dataset
«
on:
June 22, 2018, 12:29:59 am »
Hi, I'm trying to do a Select, loop through its records, then call a procedure to update each record, but I'm getting "Operation cannot be performed on an active dataset".
I wonder why this error, since my "UpdateRecords" procedure creates a new TSqlQuery instance.
Here's my code:
Code: Pascal
[Select]
[+]
[-]
Procedure
ListRecords
;
var
lSql
:
TSqlQuery
;
id
:
Integer
;
begin
lSql
:
=
TSqlQuery
.
Create
(
nil
)
;
try
lSql
.
DataBase
:
=
DataModule1
.
PQConnection1
;
lSql
.
SQL
.
Text
:
=
'select * from table'
;
lSql
.
Open
;
while
not
lSql
.
Eof
do
begin
id
:
=
lSql
.
FieldByName
(
'id'
)
.
AsInteger
;
UpdateRecord
(
id
)
;
lSql
.
Next
;
end
;
finally
lSql
.
Free
;
end
;
end
;
Procedure
UpdateRecords
(
Id
:
Integer
)
;
var
lSql
:
TSqlQuery
;
begin
lSql
:
=
TSqlQuery
.
Create
(
nil
)
;
try
lSql
.
DataBase
:
=
DataModule1
.
PQConnection1
;
lSql
.
Transaction
:
=
DataModule1
.
SqlTransaction1
;
lSql
.
SQL
.
Text
:
=
'update table set read=true where id=:id'
;
lSql
.
ParamByName
(
'id'
)
.
AsInteger
:
=
id
;
lSql
.
ExecSql
;
DataModule1
.
SqlTransaction1
.
Commit
;
finally
lSql
.
Free
;
end
;
end
;
«
Last Edit: June 22, 2018, 02:06:15 pm by martinrame
»
Logged
valdir.marcos
Hero Member
Posts: 1106
Re: Operation cannI t be performed on an active dataset
«
Reply #1 on:
June 22, 2018, 05:16:10 am »
Why are you slowly updating all that on the client side instead of using the faster server side?
Code: SQL
[Select]
[+]
[-]
UPDATE
TABLE
SET
READ
=
TRUE
WHERE
id
IN
(
SELECT
id
FROM
TABLE
WHERE
condition
=
:condition
)
;
«
Last Edit: June 22, 2018, 05:34:23 am by valdir.marcos
»
Logged
martinrame
Full Member
Posts: 119
Re: Operation cannI t be performed on an active dataset
«
Reply #2 on:
June 22, 2018, 02:01:43 pm »
This is an example, not real code.
Inside my ListRecords function I do many more operations (that cannot be done in the database) than just updating records from the same table.
Logged
martinrame
Full Member
Posts: 119
Re: Operation cannot be performed on an active dataset
«
Reply #3 on:
June 22, 2018, 02:11:03 pm »
Sorry, the error does not comes from this code, but from a nested query I'm doing against an SQLServer Database.
I'll try to isolate it, then come bak.
Logged
martinrame
Full Member
Posts: 119
[SOLVED] Re: Operation cannot be performed on an active dataset
«
Reply #4 on:
June 22, 2018, 02:18:12 pm »
The solution was NOT commiting inside the nested procedure (the one tha does .ExecSQL), but commiting when the main loop ends.
Logged
rvk
Hero Member
Posts: 6170
Re: Operation cannot be performed on an active dataset
«
Reply #5 on:
June 22, 2018, 02:19:59 pm »
My guess is that DataModule1.SqlTransaction1 is also connected to the query in ListRecords (via the database connection in DataModule1). Committing that transaction will also close the query in ListRecords.
You need to re-think the flow or set the correct parameter for the transaction that it will not close the queries automatically. Rethinking the flow is the better choice. Maybe use a separate transaction in UpdateRecords().
Edit: Ah, you already found it
Logged
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