Select a smart large object

A SELECT statement does not perform the actual output for the smart-large-object data. It does, however, establish a means for the application program to identify a smart large object so that it can then issue library functions to open, read, write, or perform other operations on the smart large object.

A CLOB or BLOB column in a database table contains the LO-pointer structure for a smart large object. Therefore, when you select a CLOB or BLOB column into an ifx_lo_t host variable, the SELECT statement returns an LO-pointer structure. For this reason, you declare host variables for CLOB and BLOB values as LO-pointer structures.

The following figure shows how the database server transfers the data of a smart large object to the client application.

For an example of code that selects a smart large object from a database column, see The create_clob.ec program. For information about how to store a smart large object in the database, see Store a smart large object.