mysql - 我有一个计算并返回客户余额的函数，但它向我返回以下错误

Question

CREATE DEFINER=`root`@`%` FUNCTION  CalSoldeClient (vID_Cli int) RETURNS double
DETERMINISTIC
BEGIN
DECLARE Solde Double;

select sum(Mt_Reg) SumMtReg from t_regcli where id_Cli = vID_Cli;

select sum(Mt_Credit) SumMtCredit from t_credit where id_Cli = vID_Cli;

select SoldeInit from t_clients where id = vID_Cli;

set Solde = SumMtReg - (SumMtCredit +  SoldeInit);


RETURN Solde;
END

ERROR 1415：不允许从函数返回结果集

Answer 1

如果您需要在 var 中选择 select 的结果，您应该使用 SELECT INTO 来声明正确的 var

  CREATE DEFINER=`root`@`%` FUNCTION  CalSoldeClient (vID_Cli int) RETURNS double
  DETERMINISTIC
  BEGIN
  DECLARE IntoSoldeInit Double;
  DECLARE SumMtReg Double;
  DECLARE SumMtCredit Double;
  DECLARE Solde Double;

  select sum(Mt_Reg) INTO SumMtReg from t_regcli where id_Cli = vID_Cli;

  select sum(Mt_Credit) INTO SumMtCredit from t_credit where id_Cli = vID_Cli;

  select SoldeInit INTO  IntoSoldeInit from t_clients where id = vID_Cli;

  set Solde = SumMtReg - (SumMtCredit +  IntoSoldeInit);


  RETURN Solde;
  END