如何从 OCI 调用 ORACLE 函数？
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How do I call an ORACLE function from OCI?
提问by David
I can call an ORACLE stored procedure through OCI in a C program by constructing the SQL command for the command, here's a brief snippet from my code:
我可以通过为命令构造 SQL 命令，在 C 程序中通过 OCI 调用 ORACLE 存储过程，这是我的代码中的一个简短片段：
/* build sql statement calling stored procedure */
strcpy ( sql_stmt, "call get_tab_info(:x)" );
rc = OCIStmtPrepare(p_sql, p_err, sql_stmt,
(ub4) strlen (sql_stmt), (ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT);
But how do I construct a call (in my C program) to an ORACLE function with the following signature:
但是我如何构造一个调用（在我的 C 程序中）具有以下签名的 ORACLE 函数：
CREATE OR REPLACE FUNCTION get_seq_number (p_table_name IN VARCHAR2, p_seq_type IN VARCHAR2)
RETURN NUMBER IS
To call the function in PL/SQL I would use for example:
要在 PL/SQL 中调用该函数，我将使用例如：
v_seq := get_seq_number(v_tabname, v_seqtype);
How do I construct the SQL character array (sql_stmt) to call the ORACLE function in my C program ?
如何构造 SQL 字符数组 (sql_stmt) 以在我的 C 程序中调用 ORACLE 函数？
回答by Thomas Jones-Low
Construct your SQL statment as follows
构造您的 SQL 语句如下
strcpy ( sql_stmt, "BEGIN :v_seq := get_seq_number(:v_tabname, :v_seqtype); END;" );
Prepare your statement as previously. Bind the variables by name (including the v_seqas previous in your code and execute the statement. When the procedure completes, the value of :v_seq will be set correctly.
像以前一样准备你的陈述。按名称绑定变量（包括v_seq前面代码中的变量并执行该语句。过程完成后，:v_seq 的值将被正确设置。
回答by Quassnoi
You either issue:
你要么发出：
SELECT my_udf()
FROM dual
and parse the result as in SELECT query, or call anonymous block:
并将结果解析为SELECT query，或调用匿名块：
BEGIN
:test := my_udf();
END;
, and bind :testas an output parameter.
, 并:test作为输出参数绑定。
