DELIMITER //

CREATE OR REPLACE FUNCTION zen_get_keyvalue(
  p_tablename VARCHAR(100),
  p_fieldname VARCHAR(20)
) 
RETURNS TEXT
DETERMINISTIC
/*
  Function   : 改寫成 api 給 amis 呼叫時, 如果一個 Form 上有多個 select 是固定內容
  Description: 如上
  Build Date : 2022/02/16
  
  Modify History
    Item Who        Date       Modify Docs
    ===M= ========== ========== ================================================
    1    Michael    2022/02/16 Init 
*/
BEGIN
  DECLARE v_cnt INT;
  DECLARE v_crlf VARCHAR(2);
  DECLARE v_comma VARCHAR(1);
  DECLARE v_value VARCHAR(100);
  DECLARE v_label VARCHAR(100);
  DECLARE v_rets TEXT;
  DECLARE v_imax INT;
  DECLARE v_inow INT;
  DECLARE v_rowid INT DEFAULT 1;
  
  -- 臨時表儲存 JSON 數據
  DROP TEMPORARY TABLE IF EXISTS temp_jsondata;
  CREATE TEMPORARY TABLE temp_jsondata (
    rowid INT AUTO_INCREMENT PRIMARY KEY,
    value VARCHAR(100),
    label VARCHAR(100)
  );
  
  SET v_crlf = CONCAT(CHAR(13), CHAR(10));
  
  -- 檢查是否有設定到 tablename
  SELECT COUNT(*) INTO v_cnt FROM zen_keyvalue 
  WHERE tablename = p_tablename AND fieldname = p_fieldname;
  
  IF v_cnt > 0 THEN
    INSERT INTO temp_jsondata (value, label)
    SELECT keyid AS value, keyvalue AS label 
    FROM zen_keyvalue 
    WHERE tablename = p_tablename AND fieldname = p_fieldname;
  ELSE
    INSERT INTO temp_jsondata (value, label)
    SELECT keyid AS value, keyvalue AS label 
    FROM zen_keyvalue 
    WHERE tablename = 'xxxx' AND fieldname = p_fieldname;
  END IF;
  
  -- 回傳 options []
  SELECT COUNT(*) INTO v_imax FROM temp_jsondata;
  SET v_inow = 1;
  SET v_rets = '';
  SET v_comma = ',';
  
  WHILE v_inow <= v_imax DO
    IF v_inow = v_imax THEN
      SET v_comma = '';
    END IF;
    
    SELECT value, label INTO v_value, v_label 
    FROM temp_jsondata 
    WHERE rowid = v_inow;
    
    SET v_rets = CONCAT(v_rets,
          '         {', v_crlf, 
          '            "label": "', v_label, '",', v_crlf, 
          '            "value": "', v_value, '"', v_crlf, 
          '          }', v_comma, v_crlf);
    
    SET v_inow = v_inow + 1;
  END WHILE;
  
  SET v_rets = CONCAT('"options": [ ', v_rets, ' ],', v_crlf);
  
  DROP TEMPORARY TABLE IF EXISTS temp_jsondata;
  
  RETURN v_rets;
END //

DELIMITER ;