Call the database server

Executing an SQL statement is essentially calling the database server as a subroutine. Information must pass from the program to the database server, and information must be returned from the database server to the program.

Some of this communication is done through host variables. You can think of the host variables named in an SQL statement as the parameters of the procedure call to the database server. In the preceding example, a host variable acts as a parameter of the WHERE clause. Host variables receive data that the database server returns, as Retrieve multiple rows describes.

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