如何用oracle数据库完成4张表的连接和查询？？？

oracle同时查询多张表较为简单，用sql和视图都可以完成，但是oracle查询多张视图就不好做了，要是还有分页和检索的功能就更加蛋疼了，今天老夫遇到了这样的问题，接下来就和大伙分享下：

//分页的语句

String fenyeSql_1 = "SELECT * FROM ( SELECT A.*, ROWNUM RN FROM ("

String fenyeSql_2 = " ) A WHERE ROWNUM <= " + end + " ) WHERE RN >= "+ from + " "

//查询条数的语句

String fenyeCountSql_1 = " select count(*) from ( "

String fenyeCountSql_2 = " ) "

String union = " union "

//第一张视图

String sql_gjy_select = " select to_char(t.xm) xm,to_char(t.xb) xb,t.qslc qslc,t.zzlc ,to_char(t.检查日期) 检查日期,to_char(t.上传时间) 上传时间,t.上传单位,t.路局名,t.jcsbid sclx from v$gwsj_jcsjlx t where 1=1 "

//第二张视图

String sql_tqi_select = " select t2.xm xm,t2.xb xb,t2.qslc qslc,t2.zzlc,to_char(t2.检查日期,'yyyy-MM-dd') 检查日期,to_char(t2.上传时间,'yyyy-MM-dd') 上传时间,t2.上传单位,t2.路局名,4 sclx from v$tqi_line t2 where 1=1 "

//第三张视图

String sql_g4d_select = " select t3.xm xm,t3.xb xb,t3.qslc qslc,t3.zzlc,t3.检查日期 检查日期,to_char(t3.上传时间,'yyyy-MM-dd') 上传时间,t3.上传单位,t3.路局名,5 sclx from v$g4d_line t3 where 1=1 "

//注意三张视图的数据类型要转换一致，而且列的数量要一样哦

//接下来就是蛋疼的凭借sql

// 条件1

if (null != year &&null != month &&!"".equals(year)

&&!"".equals(month)) {

String selectDate = year + "-"

if (month.toCharArray().length == 1) {

selectDate += "0" + month

} else if (month.toCharArray().length == 2) {

selectDate += month

}

sql_gjy_select += " and t.检查日期 like '%" + selectDate + "%'"

sql_tqi_select += " and t2.检查日期 like '%" + selectDate + "%'"

sql_g4d_select += " and t3.检查日期 like '%" + selectDate + "%'"

}

//条件2

if (null != fdwbh &&!"".equals(fdwbh)) {

sql_gjy_select += " and t.上传单位='" + fdwbh + "'"

sql_tqi_select += " and t2.上传单位='" + fdwbh + "'"

sql_g4d_select += " and t3.上传单位='" + fdwbh + "'"

}

//

//

中间条件省略若干的

//

//

// 查询数据

String sql_select = fenyeSql_1 + sql_gjy_select + union

+ sql_tqi_select + union + sql_g4d_select + fenyeSql_2

// 对应总条数

String sql_count = fenyeCountSql_1 + sql_gjy_select + union

+ sql_tqi_select + union + sql_g4d_select + fenyeCountSql_2

PreparedStatement ps = null

String permissionJson = null

--是这种关联查询？

select a.col1,b.col2,c.col3,d.col4 

from tab1 a, tab2 b, tab3 c, tab4 d

where a.col11=b.col21 and a.col12=c.col31 and c.col32=d.col41

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