SQL statements are placed (embedded) within regular C or C++ code. All embedded SQL statements start with the words EXEC SQL and end with a semicolon (;). Normal C language comments are allowed in the middle of embedded SQL statements.
Every C program using embedded SQL must contain the following statement before any other embedded SQL statements in the source file.
EXEC SQL INCLUDE SQLCA;
The first embedded SQL statement executed by the C program must be a CONNECT statement. The CONNECT statement is used to establish a connection with the database server and to specify the user ID that is used for authorizing all statements executed during the connection.
Some embedded SQL commands do not generate any C code, or do not involve communication with the database. These commands are thus allowed before the CONNECT statement. Most notable are the INCLUDE statement and the WHENEVER statement for specifying error processing.