October 2015 ~ LEARN MS-ACCESS TIPS AND TRICKS

Sunday, October 11, 2015

RUNSQL Action in MACRO and VBA

Introduction.

The Microsoft Access beginners can get confused with the usage of RUNSQL Action in Macro and DoCmd.RUNSQL method of Visual Basic for Applications (VBA). Whether you run this Action in Macro or in VBA you must provide the SQL Statement of an Action-Query or Data-Definition Query Types only. If you are not sure which are these types of queries then refer to the following list:

Action Query Type.

**Action Query Types**
Query Type	Statement
Append	INSERT INTO
Delete	DELETE
Make-Table	SELECT ... INTO
Update	UPDATE

Data Definition Queries.

**Data-Definition Query Types**
Query Type	Statement
Create a table	CREATE TABLE
Alter a table	ALTER TABLE
Delete a table	DROP TABLE
Create an Index	CREATE INDEX
Delete an Index	DROP INDEX

Using the SQL Statement of any other Query type in RUNSQL Action will end up in errors. In Macro the length of an SQL statement can be a maximum of 256 characters or less.

The DoCmd.RUNSQL method of VBA can execute an SQL statement with a maximum length of 32768 characters or less.

Note: You are not allowed to give an existing Query Name as a parameter to this command. But, in VBA you can load the SQL Statement of a predefined query into a String Variable and use it as the parameter to the DoCmd.RUNSQL command.

Example-1:

Public Function DelRecs()
'Existing Delete Query’s SQL is used in this example
Dim db As Database, qryDef As QueryDef
Dim strSQL As String

'Read and save the SQL statement from 'Query48'
'and load into strSQL string variable
Set db = CurrentDb
Set qryDef = db.QueryDefs("Query48")
strSQL = qryDef.SQL

'Execute the SQL statement after
'disabling warning messages
DoCmd.SetWarnings False
DoCmd.RunSQL strSQL
DoCmd.SetWarnings True

'Using DoCmd.OpenQuery Command to run a Delete Query
DoCmd.SetWarnings False
DoCmd.OpenQuery "Query48", acViewNormal
DoCmd.SetWarnings True

End Function

The RUNSQL Action of Macro Modifies/Deletes information of several records in one go. Before executing the Action Query Microsoft Access gives out a warning message, appropriate to the action specified, and waits for the User's responses. The User must respond to proceed/cancel the action specified.

Once the procedure is perfected, by test running the Action Query several times, we can ask Microsoft Access to turn OFF the Warning Messages during the execution of RUNSQL Action. After the Query running step, give control back to MS-Access by turning ON the Warning Message detection. From that point onwards MS-Access will be watching for unexpected errors in the System and warns the User, as and when it happens.

The SetWarnings Action in Macro and DoCmd.SetWarnings Method in VBA is used for this purpose when data processing for a report involves one or more action query steps placed in a Macro. Check the image of a Macro, given below in the design view, with the SetWarnings settings, before and after the RUNSQL Action in the Macro. The first Action in the Macro is Setwarnings with the Parameter value NO to turn off the Warning Messages when the RUNSQL Action executes in the next step. The SetWarnings Action with the Parameter value YES turns ON the Warning Messages in step three, so that MS-Access can take care of future unexpected System Errors of any kind, as and when it happens.

Example-2:

Create a Table with the Data-definition SQL

Warning: Double-check that you are not using any existing table name for this sample run.

Public Function DataDefQuery()
Dim strSQL As String

strSQL = "CREATE TABLE Books  (Title TEXT(50) NOT NULL, Author TEXT(50) NOT NULL, PublishDate DATE, Price CURRENCY)"

DoCmd.RunSQL strSQL

End Function

The OpenQuery Action in Macro and DoCmd.OpenQuery Method of VBA uses the name of a predefined Query (of any type) to open them in any of the following Views: