# TYPE ## Name TYPE -- 定义新的数据类型 ## Synopsis ``` TYPE _type_name_ IS _ctype_ ``` ## 描述 `TYPE`命令定义一个新的C类型。 它相当于将`typedef`放到声明段中。 当运行带有`-c`选项的`ecpg`的时候， 仅仅标识该命令。 ## 参数 `_type_name_` 新类型名字。它必须是一个有效的C类型名字。 `_ctype_` C类型说明。 ## 例子 ``` EXEC SQL TYPE customer IS struct { varchar name[50]; int phone; }; EXEC SQL TYPE cust_ind IS struct ind { short name_ind; short phone_ind; }; EXEC SQL TYPE c IS char reference; EXEC SQL TYPE ind IS union { int integer; short smallint; }; EXEC SQL TYPE intarray IS int[AMOUNT]; EXEC SQL TYPE str IS varchar[BUFFERSIZ]; EXEC SQL TYPE string IS char[11]; ``` 这里是使用`EXEC SQL TYPE`的例子程序： ``` EXEC SQL WHENEVER SQLERROR SQLPRINT; EXEC SQL TYPE tt IS struct { varchar v[256]; int i; }; EXEC SQL TYPE tt_ind IS struct ind { short v_ind; short i_ind; }; int main(void) { EXEC SQL BEGIN DECLARE SECTION; tt t; tt_ind t_ind; EXEC SQL END DECLARE SECTION; EXEC SQL CONNECT TO testdb AS con1; EXEC SQL SELECT current_database(), 256 INTO :t:t_ind LIMIT 1; printf("t.v = %s\n", t.v.arr); printf("t.i = %d\n", t.i); printf("t_ind.v_ind = %d\n", t_ind.v_ind); printf("t_ind.i_ind = %d\n", t_ind.i_ind); EXEC SQL DISCONNECT con1; return 0; } ``` 该程序的输出看起来像这样： ``` t.v = testdb t.i = 256 t_ind.v_ind = 0 t_ind.i_ind = 0 ``` ## 兼容性 `TYPE`命令是PostgreSQL的扩展。