Usage

The base.SqlHandle class is a built-in class providing dynamic SQL support with a 3GL API.

Compared to regular SQL cursor instructions, the main purpose of the base.SqlHandle class is to provide column name and SQL data type information with the getResultName() and getResultType() methods. It is also possible to write generic code for parameterized queries with the setParameter() method.

Note:

A database connection must exist in order to use SqlHandle objects.

Unlike regular Genero cursors, SQL handle objects are created dynamically, and can be passed as parameter or returned from functions:
MAIN
   DEFINE h base.SqlHandle
   CONNECT TO "mydb"
   LET h = base.SqlHandle.create()
   CALL my_prepare(h)
   CALL my_execute(h)
END MAIN

FUNCTION my_prepare(h)
   DEFINE h base.SqlHandle
   CALL h.prepare("INSERT INTO cust VALUES ( ...
END FUNCTION

FUNCTION my_execute(h)
   DEFINE h base.SqlHandle
   CALL h.execute()
END FUNCTION

Executing a simple SQL statement without a result set

Perform the following steps, to execute a SQL statement without a result set:

  1. Define the SQL handle variable as base.SqlHandle
  2. Create a SQL handle object base.SqlHandle.create()
  3. prepare(sql-text)
  4. For each SQL parameter:
    1. setParameter(index, value)
  5. execute() -- test for sqlca.sqlcode
  6. Repeat from (5), (4), or (3)

Executing a SQL statement returning a result set

Perform the following steps, to execute a SQL statement with a result set:

  1. Define the SQL handle variable as base.SqlHandle
  2. Create a SQL handle object base.SqlHandle.create()
  3. prepare(sql-text)
  4. For each SQL parameter:
    1. setParameter(index, value)
  5. open()
  6. fetch() -- test for sqlca.sqlcode == 100
  7. getResultCount() -- for each column index:
    1. getResultName(index)
    2. getResultType(index)
    3. getResultValue(index)
  8. close()
  9. Repeat from (6), (4), (5), or (3)

Executing a SQL statement returning a result set, as scrollable cursor

Perform the following steps, to execute a SQL statement with a result set and scroll forwards and backwards in the rows:

  1. Define the SQL handle variable as base.SqlHandle
  2. Create a SQL handle object base.SqlHandle.create()
  3. prepare(sql-text)
  4. For each SQL parameter:
    1. setParameter(index, value)
  5. openScrollCursor()
  6. fetch() (next row), fetchLast(), fetchFirst(), fetchPrevious(), fetchRelative(n) or fetchAbsolute(n) -- test for sqlca.sqlcode == 100
  7. getResultCount() -- for each column index:
    1. getResultName(index)
    2. getResultType(index)
    3. getResultValue(index)
  8. close()
  9. Repeat from (6), (4), (5), or (3)

Creating rows with an insert cursor

Perform the following steps, to insert many rows with an SQL handle insert cursor:

  1. Define the SQL handle variable as base.SqlHandle
  2. Create an SQL handle object base.SqlHandle.create()
  3. prepare(insert-stmt-with-params)
  4. BEGIN WORK
  5. open()
  6. For each row to insert:
    1. For each SQL parameter:
      1. setParameter(index, value)
    2. put()
  7. close()
  8. COMMIT WORK
  9. Repeat from (4) or (3)

SQL error handling with SqlHandle

Handling SQL error and status information (such as NOTFOUND) can be done with SqlHandle objects as with regular SQL instruction, by testing the sqlca.sqlcode register, and by using TRY/CATCH blocks or WHENEVER ERROR.
MAIN
   DEFINE h base.SqlHandle
   CONNECT TO "mydb"
   LET h = base.SqlHandle.create()
   TRY
       CALL h.prepare("SELECT * FROM mytab")
       CALL h.open()
       CALL h.fetch()
       DISPLAY h.getResultValue(1)
       CALL h.close()
   CATCH
       DISPLAY "SQL ERROR:", sqlca.sqlcode
   END TRY
END MAIN