The DB_Api functions DB_ExecDirect and DB_Prepare work with SQL commands defined in your dclsql section. SQL commands you use in these DB_Api functions must be declared in a dclsql section of your script. You cannot use SQL commands in DB_Api functions that use parameters.
var c1: cursor; dcltrans transaction DBApiSelling begin ... DB_Prepare(c1, SelArticle); ... end DBApiSelling; dclsql SelArticle: SELECT * FROM article WHERE a_stock > 5 AND a_price > 1000;