Postgres数据库organization表: CREATE TABLE ORGANIZATION( -- 分公司与部门表 DWBH INTEGER NOT NULL, -- 部门ID DWMC VARCHAR(50) NOT NULL, --部门名称 FGS INTEGER NOT NULL, --分公司ID FGSMC VARCHAR(50) NOT NULL --分公司名称 ) 优化前: select concat(fgsmc,'---',dwmc) as dwmc from organization where fgsmc!=dwmc union all select distinct dwmc from organization where fgsmc=dwmc 优化后: select case when fgsmc!=dwmc then concat(fgsmc,'---',dwmc) when fgsmc=dwmc then dwmc end as dwmc from organization
数据库SQL优化
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