Union All拼接Sql語句做批量新增
阿新 • • 發佈：2018-12-23
上篇文章《多種方法實現Excel批量匯入資料庫》說到，批量匯入用了拼接Insert語句的方式進行，這種方式簡單來說是把要匯入的每條資料都拼接成一條Insert語句， 然後同時執行實現的。但是經過領導提醒，又用了另外一種方式，那就是用Union All做合併，合併完一張表之後，整張表匯入。下面就簡單介紹一下。
Union All是做聯表查詢的，平常的用法是：
union all在這裡的用法是，查詢Table1的時候，先查詢Table2的所有欄位，將所有欄位和Table2合併起來，然後顯示出來。union同樣也能做這個功能，不過二者有一點區別。union合併的時候，是兩張表相同的欄位合併為一個欄位，而union all做到的是整張表所有的欄位都合併給Table1。<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="font-family:KaiTi_GB2312;font-size:18px;">select * from Table1 union all select * from Table2</span></span>
在我們這個系統中，是將union all放到了insert語句中，簡單介紹一下程式碼：
直接拼接Insert語句，得到的SQL語句是這個樣子的：<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="font-family:KaiTi_GB2312;font-size:18px;"> #region 批量新增實體 /// <summary> /// 批量新增實體 /// </summary> /// <param name="settingevaluation">要匯入資料庫的資料組成的泛型集合</param> /// <returns></returns> public bool Insert(List<YzSettingEvaluationEntity> settingevaluation) { //開啟資料庫連線 SQLHelper sqlHelper = new SQLHelper("YzEvaluationSystemEntities"); StringBuilder sbSql = new StringBuilder(); //迴圈實體list，進行拼接 if (settingevaluation.Count > 1) { sbSql.Append("insert into YzSettingEvaluationEntity(ID,EvaluatorID,CriticID,IsEvaluated,Weight,Year,EvaluationInfoID,IsUsed) "); for (int i = 0; i < settingevaluation.Count - 1; i++) { sbSql.Append("select "); sbSql.Append("'" + settingevaluation[i].ID + "',"); sbSql.Append("'" + settingevaluation[i].EvaluatorID + "',"); sbSql.Append("'" + settingevaluation[i].CriticID + "',"); sbSql.Append(0 + ","); sbSql.Append("'" + settingevaluation[i].Weight + "',"); sbSql.Append("'" + settingevaluation[i].Year + "',"); sbSql.Append("'" + settingevaluation[i].EvaluationInfoID + "',"); sbSql.Append(1); sbSql.Append(" union all "); } sbSql.Append("select "); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].ID + "',"); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].EvaluatorID + "',"); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].CriticID + "',"); sbSql.Append(0 + ","); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].Weight + "',"); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].Year + "',"); sbSql.Append("'" + settingevaluation[settingevaluation.Count - 1].EvaluationInfoID + "',"); sbSql.Append(1); sbSql.Append(";"); } YzSettingEvaluationEntity set = new YzSettingEvaluationEntity(); var lists = new[] { "ID", "EvaluatorID", "CriticID", "IsEvaluated", "Weight", "Year", "EvaluationInfoID", "IsUsed" }; //呼叫sqlhelper方法進行新增。 int flag = sqlHelper.ExecuteNonQuery(sbSql.ToString(), System.Data.CommandType.Text); if (flag > 0) { return true; } else { return false; } } #endregion</span></span>
而用union all拼接完的SQL語句的樣子是這樣的：<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="font-family:KaiTi_GB2312;font-size:18px;">insert into YzStaffEntity(ID,StaffName,StaffPassword,StaffID,Sex,IdentityCard,Subject,WorkDate,EngageDate,jobQualification,DivisionID,SeriesID,PositionID,IsUsed) values ('813a3a46-df83-49bf-8b78-d39f6ee73fa8','何志強','151035','1','男','132827196412151035','','1985/8/1 0:00:00','','中教高階','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','dc1166b7-d394-437c-bf12-a86e488ae930','1' ) insert into YzStaffEntity(ID,StaffName,StaffPassword,StaffID,Sex,IdentityCard,Subject,WorkDate,EngageDate,jobQualification,DivisionID,SeriesID,PositionID,IsUsed) values ('8572db21-930f-4c53-8282-d8dbafd0b9c5','劉懷增','054414','2','男','132801196306054414','','1982/4/1 0:00:00','','','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','cf0ade2f-3ed7-4fbb-b693-70b98e014ea8','1' ) insert into YzStaffEntity(ID,StaffName,StaffPassword,StaffID,Sex,IdentityCard,Subject,WorkDate,EngageDate,jobQualification,DivisionID,SeriesID,PositionID,IsUsed) values ('0e6b61d4-6fb5-4d83-88bd-e20ba0e2afb3','劉文俊','170819','3','男','132801196110170819','','1986/7/1 0:00:00','','中教高階','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','cf0ade2f-3ed7-4fbb-b693-70b98e014ea8','1' )</span></span>
<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="font-family:KaiTi_GB2312;font-size:18px;">insert into YzSettingEvaluationEntity(ID,EvaluatorID,CriticID,IsEvaluated,Weight,Year,EvaluationInfoID,IsUsed) select 'd000917f-9ebd-45e5-a574-0f2fa57539ad','63eff2c1-0dc8-4822-8664-1e54d9e632ec','439b6794-7467-4623-a8f6-0756c12e3eb5',0,'f87680ce-1cb4-d2d0-7aa5-04a6c5c3edf6','621541d6-1697-fb82-fc14-8540ff1cf000','0b2bc4cd-ac5f-412e-a227-c3b4ac61ddc5',1 union all
select '6977b00d-94ea-442f-b22e-fd296c54d2e1','63eff2c1-0dc8-4822-8664-1e54d9e632ec','51c11fd2-65ca-4c61-9e13-0c44c735e4bd',0,'f87680ce-1cb4-d2d0-7aa5-04a6c5c3edf6','621541d6-1697-fb82-fc14-8540ff1cf000','0b2bc4cd-ac5f-412e-a227-c3b4ac61ddc5',1 union all
select '303de911-52cc-4e20-ba88-6b301c59728a','63eff2c1-0dc8-4822-8664-1e54d9e632ec','09bd256e-eda4-47e4-bbe6-0e68eb472659',0,'f87680ce-1cb4-d2d0-7aa5-04a6c5c3edf6','621541d6-1697-fb82-fc14-8540ff1cf000','0b2bc4cd-ac5f-412e-a227-c3b4ac61ddc5',1 union all;
</span></span>在我們拼接SQL語句的過程中，還用過一種拼接Insert語句，拼接完的效果是：
<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="font-family:KaiTi_GB2312;font-size:18px;">insert into YzStaffEntity(ID,StaffName,StaffPassword,StaffID,Sex,IdentityCard,Subject,WorkDate,EngageDate,jobQualification,DivisionID,SeriesID,PositionID,IsUsed) values ('813a3a46-df83-49bf-8b78-d39f6ee73fa8','何志強','151035','1','男','132827196412151035','','1985/8/1 0:00:00','','中教高階','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','dc1166b7-d394-437c-bf12-a86e488ae930','1' ),
('8572db21-930f-4c53-8282-d8dbafd0b9c5','劉懷增','054414','2','男','132801196306054414','','1982/4/1 0:00:00','','','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','cf0ade2f-3ed7-4fbb-b693-70b98e014ea8','1' ),
('0e6b61d4-6fb5-4d83-88bd-e20ba0e2afb3','劉文俊','170819','3','男','132801196110170819','','1986/7/1 0:00:00','','中教高階','3b253d62-54f9-4dd2-9897-7c8da7107693','e1a5eec0-d61f-4d55-86e2-fbffae1a4fdd','cf0ade2f-3ed7-4fbb-b693-70b98e014ea8','1' )
</span></span>總結
記憶很深的有一節米老師講的課，主題是人生如程式碼，程式碼如人生，越來越能體會到這句話的含義。你的程式碼就像你的人生一樣，人生路上有很多個岔路口，每經過一個岔路口都需要你做出選擇，程式碼也一樣。實現同一個功能的方式有很多，關鍵是要選擇最適合的那個。而且程式碼需要用心去寫，就像你的路需要用心去走一樣。