Which node are you using to do the query? DbQuery doesn't support variables. You'd have to use DbExecute.
query="SELECT * FROM TESTTABLE WHERE Test = :?"
sqlSelect(1,query,myField)
in this case,
"Test" must be the name of a column in the database
"myField" must be a name of an input column
The two names can be identical. I am just demonstrating that they can be different.
I have seen a few implementations where this will work;
query="SELECT * FROM TESTTABLE WHERE Test = :myField"
sqlSelect(1,query,myField)
but you still have to name the input column as a "Bind Column" on the sqlSelect statement.
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If you are using JDBC nodes (any of them), you must put the input column name into the parameter "SqlQueryFieldBindings" and then you can use :? or :myField in the query