使用 if 语句的休眠查询答案

【问题标题】：Hibernate query using if statement使用 if 语句的休眠查询
【发布时间】：2015-08-28 17:52:24
【问题描述】：

我正在尝试编写一个休眠查询，我正在使用 StringBuilder 并为 ce、pe 和两者设置 3 个单独的字符串集。如何将它添加到我的休眠查询中？我想将它添加到我添加评论以“在此处添加标志”的位置。我的标志类型是枚举“Y”或“N”。

        StringBuffer queryByCos4Allocation = new StringBuffer();
    Flag ceIngress = null;
    Flag ceEgress = null;
    Flag peIngress = null;
    Flag peEgress = null;
    String      ce = null;
    String      pe = null;
    String both = null;

    if (Flag.Y.equals(ceIngress) || Flag.Y.equals(ceEgress)){
        ce =      " AND (CE_INGRESS_FLAG = 'Y' OR CE_EGRESS_FLAG = 'Y')  "
                + " AND (PE_INGRESS_FLAG = 'N' OR PE_EGRESS_FLAG = 'N') " ;
    }if (Flag.Y.equals(peIngress) || Flag.Y.equals(peEgress)){
        pe =      " AND (CE_INGRESS_FLAG = 'N' OR CE_EGRESS_FLAG = 'N')  "
                + " AND (PE_INGRESS_FLAG = 'Y' OR PE_EGRESS_FLAG = 'Y') " ;
    }if (ce == pe){
        both =    " AND (CE_INGRESS_FLAG = 'Y' OR CE_EGRESS_FLAG = 'Y')  "
                + " AND (PE_INGRESS_FLAG = 'Y' OR PE_EGRESS_FLAG = 'Y') " ;
    }

    queryByCos4Allocation.append("  SELECT * FROM TRAFFIC_PROFILE " ).append( 
                "   WHERE COS_MODEL = 'cos4'  " ).append(
                "   AND DIRECTION = ?  " ).append(
                        /* 
                         * add my Flag case here 
                         * */
                "   and  TRAFFIC_PROFILE_ID IN " ).append(
                "   ( " ).append(
                "   select distinct (C1.Traffic_PROFILE_ID) from Cos_Class_Allocation C1, " ).append(
                "   Cos_Class_Allocation C2, Cos_Class_Allocation C3, Cos_Class_Allocation C4  " ).append(
                "   where c1.class_name = 'COS1' AND c1.CLASS_ALLOCATION = ? " ).append(
                "   and c2.class_name = 'COS2' AND c2.CLASS_ALLOCATION = ? " ).append(
                "   and c3.class_name = 'COS3' AND c3.CLASS_ALLOCATION = ? " ).append(
                "   and c4.class_name = 'COS4' AND c4.CLASS_ALLOCATION = ? " ).append(
                "   and C1.TRAFFIC_PROFILE_ID = c2.TRAFFIC_PROFILE_ID " ).append(
                "   and C1.TRAFFIC_PROFILE_ID = c3.TRAFFIC_PROFILE_ID " ).append(
                "   and C1.TRAFFIC_PROFILE_ID = c4.TRAFFIC_PROFILE_ID); " );

【问题讨论】：

小心，ce==pe 不对，是字符串，必须和.equals比较
您想在代码中添加 ce、pe 还是两者都添加？
为 ifs 创建一个自己的方法并在那里返回 String。其他选项是使用更动态的标准。
@melli-182 是附加取决于 if 语句条件

标签： java sql hibernate

【解决方案1】：

使用另一个变量来存储您要附加的代码部分：

StringBuffer queryByCos4Allocation = new StringBuffer();
Flag ceIngress = null;
Flag ceEgress = null;
Flag peIngress = null;
Flag peEgress = null;
String      ce = null;
String      pe = null;
String both = null;
String toAppend = "";

if (Flag.Y.equals(ceIngress) || Flag.Y.equals(ceEgress)){
    ce =      " AND (CE_INGRESS_FLAG = 'Y' OR CE_EGRESS_FLAG = 'Y')  "
            + " AND (PE_INGRESS_FLAG = 'N' OR PE_EGRESS_FLAG = 'N') ";
    toAppend=ce;
}if (Flag.Y.equals(peIngress) || Flag.Y.equals(peEgress)){
    pe =      " AND (CE_INGRESS_FLAG = 'N' OR CE_EGRESS_FLAG = 'N')  "
            + " AND (PE_INGRESS_FLAG = 'Y' OR PE_EGRESS_FLAG = 'Y') " ;         toAppend=pe;
}if (ce!=null && ce.equals(pe)){
    both =    " AND (CE_INGRESS_FLAG = 'Y' OR CE_EGRESS_FLAG = 'Y')  "
            + " AND (PE_INGRESS_FLAG = 'Y' OR PE_EGRESS_FLAG = 'Y') " ;         toAppend=both;
}
queryByCos4Allocation.append("  SELECT * FROM TRAFFIC_PROFILE " ).append( 
            "   WHERE COS_MODEL = 'cos4'  " ).append(
            "   AND DIRECTION = ?  " ).append(
                    toAppend +
            "   and  TRAFFIC_PROFILE_ID IN " ).append(
            "   ( " ).append(
            "   select distinct (C1.Traffic_PROFILE_ID) from Cos_Class_Allocation C1, " ).append(
            "   Cos_Class_Allocation C2, Cos_Class_Allocation C3, Cos_Class_Allocation C4  " ).append(
            "   where c1.class_name = 'COS1' AND c1.CLASS_ALLOCATION = ? " ).append(
            "   and c2.class_name = 'COS2' AND c2.CLASS_ALLOCATION = ? " ).append(
            "   and c3.class_name = 'COS3' AND c3.CLASS_ALLOCATION = ? " ).append(
            "   and c4.class_name = 'COS4' AND c4.CLASS_ALLOCATION = ? " ).append(
            "   and C1.TRAFFIC_PROFILE_ID = c2.TRAFFIC_PROFILE_ID " ).append(
            "   and C1.TRAFFIC_PROFILE_ID = c3.TRAFFIC_PROFILE_ID " ).append(
            "   and C1.TRAFFIC_PROFILE_ID = c4.TRAFFIC_PROFILE_ID); " );

【讨论】：