The action executes the SQL command SELECT.

or

The keyword BIND must be followed by one of these parameters:

BIND _locVar1, _locVar2, ...
BIND _locVarRowIdent
BIND _locVarRecordIdent

The value of the parameter retCodeIdent_Int - see the table of error codes. It is possible to get extended error information.

The action SQL_SELECT enables to make SQL command SELECT as simple as possible. It combines the actions SQL_CONNECT, SQL_PREPARE, SQL_FETCH and SQL_DISCONNECT.

A database, in which the SQL command SELECT will be executed, can be defined by:

1. parameter dbObjIdent - represents the object of Database or Table type. User can enter the parameter (optional) transHandle_Int that defines a database connection (the value of parameter has been gained by previous calling the action DB_TRANS_OPEN), within it the SQL command will be executed,
   If the parameter transHandle_Int is not defined, SQL command will be executed on one of the predefined database connections.
2. parameter connectString (described on page SQL_CONNECT action). It is necessary to specify the process DB Manager that will execute the SQL command.

The command SELECT is defined by value of parameter selectIdent_String. According to the number of columns of SELECT command should be chosen the proper variant to show its result through the obligatory keyword BIND. The meaning and explanation of the variants are mentioned in action SQL_PREPARE.

An optional identifier maxRowsIdent_Int defines the row counts of select which will be returned. If it is not defined its value is 1. The number of the rows that can be read depends also on the variant BIND. Details are in the description of action SQL_FETCH.

The maximum number of returned rows is limited by a Database configuration parameter Maximum returned rows. If the number of available rows exceeds this limit, the local structure _locVarRecordIdent will contain first Maximum returned rows and retCodeIdent_Int will be set to error code _ERR_DATABASE_ROWS_LIMIT.

The values returned byt the SQL statement are inserted into local variables according to their order (1st value to the first bound variable, 2nd to the second, etc.). This also applies when inserting into a local structured variable (i.e. column names are not taken into account). Potentially dangerous are SELECTs of the "SELECT *" type - if the order of the columns in the database differs from the order of the columns in the structured variable, the values will be inserted in the wrong columns. Therefore, we recommend explicitly naming columns in SQL query (SELECT COL1, COL2, COL3 ...).

If retrieving data from a single table or view, use DBS_READ instead of SQL_SELECT.

In this example, there exists the object of Database type with the name gnat_test. There is a table OBJLIST within database in which the column id is figure.
A procedure Demo1 represents various (not all) variants of SQL_SELECT action.
The procedures Demo2 and Demo3 have the same function. Demo2 is implemented through the SQL_SELECT action and Demo3 is implemented by SQL_CONNECT action, SQL_PREPARE action, SQL_FETCH action and SQL_DISCONNECT action.

DB_TRANS_OPEN
DB_TRANS_COMMIT
DB_TRANS_ROLLBACK
DB_TRANS_CLOSE

SQL_CONNECT
SQL_EXEC_DIRECT
SQL_EXEC_PROC

SQL_PREPARE
SQL_BINDIN
SQL_FETCH
SQL_FREE

Actions for accessing a database.