Autodesk AUTOCAD 2006 Command Reference Manual page 306

[...] Button
Returns a list of available values for the specified field from the selected
database table in the Column Values Dialog Box, from which you can select
a value to apply to the query.
Add (Fields)
Adds the selected field to the SQL text editor.
Add (Operator)
Adds the selected operator to the SQL text editor.
Add (Table)
Adds the currently selected database table to the SQL text editor.
Add (Values)
Adds the value specified in the Values area to the SQL text editor.
Check
Checks your SQL query for proper syntax without actually executing it.
This function helps you isolate syntax errors before you issue your query.
Close
Closes the dialog box without issuing the query.
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