DB2的COALESCE函数

DB2的COALESCE函数

此函数相当于Oracle中的NVL且更方便,它完全可以取代SQL中的CASE.

用法:

COALESCE(A,B,C,D...);

说明:
若A为空;则取B,若B为空,则取C;...;依此类推.

用例:

        sb.append("    select ");
        sb.append("        COALESCE(t03.EMP_USER_NAME,'') as sellerName,");
        sb.append("        COALESCE(t03.EMP_LOTUS_MAIL,'') as sellerNotesMail,");
        sb.append("        COALESCE(t03.EMP_INTERNET_ID,'') as sellerIntranetId,");
        sb.append("        COALESCE(t04.BUSINESS_UNIT_NAME,'') as busiNessUnit,");
        sb.append("        COALESCE(t02.TOPT_JOB_ROLE_NAME,'') as jobRoleName,");
        sb.append("        t01.TERRITORY_NAME as territoryName");
        sb.append("    from");
        sb.append("        topt.territory  t01");
        sb.append("        left join topt.job_role   t02 on t01.ROLE_KEY=t02.ROLE_KEY  ");
        sb.append("           left join FRS.Resource    t03 on t01.EMP_UID=t03.RESOURCE_EMPLOYEE_UID");
        sb.append("        left join TOPT.BUSINESS_UNIT t04 on t01.BUSINESS_UNIT_KEY=t04.BUSINESS_UNIT_KEY        ");
        sb.append("    where ");
        sb.append("        t01.TERRITORY_KEY=? ");
        String sql = sb.toString();