我有4张table。CREATETABLEBranch(IDINT,NameVARCHAR(50));INSERTINTOBranchVALUES(1,'A'),(2,'B');CREATETABLEProduct(IDINT,NameVARCHAR(50));INSERTINTOProductVALUES(1,'X'),(2,'Y');CREATETABLEStockIn(IDINT,ProductIdINT,QuantityINT,BranchIdINT);INSERTINTOStockInVALUES(1,1,10,1),(2,1,20,1),(3,1,50,2),(4,1,10