c中嵌套sql（Nested SQL in C）.docVIP

c中嵌套sql（Nested SQL in C） One, ESQL/C learning In the C language program, nested SQL statements are used. (1) 1. Each embedded SQL statement begins with the EXEC SQL, indicating that it is a SQL statement. This also tells the compiler that the SQL statements are embedded between EXEC, SQL, and .. 2, if an embedded SQL statement takes more than one line, you can use the continuation character Fortran in the C program, and there must be continuation characters in the line. Other languages have the same rules. 3, each embedded SQL statement has the end of the symbol, such as: in C, yes;. 4, keyword embedded SQL statements are not case sensitive. 5, you can use / *... .*/ to add notes. You can also use -- to add notes (2) The embedded SQL statement should contain five steps: 1) establish the application and the SQL SERVER communication area of SQL SQLCA. 2) declare host variables. 3) connect to SQL SERVER. 4) manipulate data through the SQL statement. 5) dealing with errors and result information (3) Declare host variables The host variable (host variable) is the program variable referenced in the main program statement in the embedded SQL statement, which can be used in both the program and the embedded SQL statement. Such as: EXEC, SQL, BEGIN, DECLARE, SECTION; Char, user[31], passwd[31]; EXEC, SQL, END, DECLARE, SECTION; Explain： Before using the primary variable in the embedded SQL statement, you must use BEGIN, DECLARE, SECTION, and END DECLARE SECTION to illustrate the main variable. Be careful： 1: the primary variable is the standard C program variable. 2: embed SQL statements, use primary variables to input data and output data. Both the 3:C program and the embedded SQL statement can access the primary variable. Use： In order to facilitate identification of primary variables, when a primary variable appears in an embedded SQL statement, a colon must be marked before the variable name (:). (4) Connect database In the program, the CONNECT statement is used to conne