做报表，写Sql语句的一点收获

Sql语句一直是弱项，最近整报表可是痛苦呀，一个select能写两天。整理一下一些常用的函数和写法放在这，以后忘了来看看，呵呵（针对Oracle数据库）。例子都是生产中的例子，直接放上来保存着，后面要用的时候，我就直接复制过去用了，看起来比较费劲，例子大家还是不要看了。一、递归查询 Start with...Connect By，用于对一个树形结构的表递归遍历，Start with后面跟初始值，Connect By后面跟遍历条件。 比如： SELECT ORG_ID FROM PC_ORGANIZATION START WITH ORG_ID IN ('HBlQAIBGob')CONNECT BY PRIOR ORG_ID = PARENT_ID 二、NVL(eExpression1, eExpression2)从两个表达式返回一个非 null 值如果 eExpression1 的计算结果为 null 值，则 NVL( ) 返回 eExpression2。如果 eExpression1 的计算结果不是 null 值，则返回 eExpression1。eExpression1 和 eExpression2 可以是任意一种数据类型。如果 eExpression1 与 eExpression2 的结果皆为 null 值，则 NVL( ) 返回NULL。比如： SELECT DW, RCQ1, RCQ2, NVL(RCQ2, 0) - NVL(RCQ1, 0) FROM (SELECT DISTINCT B.ORG_NAME DW, ROUND(SUM((SELECT AVG(GAS_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE >= TO_DATE('20080529', 'YYYYMMDD') AND K.PROD_DATE <= TO_DATE('20080829', 'YYYYMMDD'))), 1) RCQ1, ROUND(SUM((SELECT AVG(GAS_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE >= TO_DATE('20080629', 'YYYYMMDD') AND K.PROD_DATE <= TO_DATE('20081029', 'YYYYMMDD'))), 1) RCQ2, FROM CD_WELL_SOURCE A, PC_ORGANIZATION_T B, PC_PRO_WELL_VOL_DAILY C WHERE C.WELL_ID = A.WELL_ID AND B.ORG_ID = A.ORG_ID AND A.ORG_ID IN (SELECT ORG_ID FROM PC_ORGANIZATION START WITH ORG_ID IN ('HBvsedjiwe') CONNECT BY PRIOR ORG_ID = PARENT_ID) GROUP BY B.ORG_NAME)
三、Round 函数对指定数值进行四舍五入 ROUND(number,[decimal_places])参数：number :预处理对数值。decimal_places : 四舍五入后保留的小数位数。示例同Nvl函数例子。四、结果集集合操作 Union、Union All、Intersect、Minus1、 Union，对两个结果集进行并集操作，不包括重复行，同时进行默认规则的排序；2、 Union All，对两个结果集进行并集操作，包括重复行，不进行排序；3、 Intersect，对两个结果集进行交集操作，不包括重复行，同时进行默认规则的排序；4、 Minus，对两个结果集进行差操作，不包括重复行，同时进行默认规则的排序。注意：如果要人为的用Oder by 排序，order by必须放在最后一个集合里面。比如： SELECT (CASE WHEN TTT.WELL_COMMON_NAME IS NULL THEN N'小计' ELSE TTT.orgname END) DW, WELL_COMMON_NAME, RQ, PUMP_JACK_WORKING_TIME, DL, MD_LANDED, TOP_MD, PUMP_DIAMETER, PUMP_EFFICIENCY, STROKE_LENGTH, STROKE_FREQUENCY, REVOLUTIONS, HYDRAULIC_HEAD, CASING_PRES, BH_PRES, START_FLUID_LEVEL_MD, WATER_QUALITY_COLOR, RCQ, LCQ, LCS, QDB, RFKQL, BZ FROM (SELECT * FROM (SELECT F.ORG_NAME ORGNAME, NULL WELL_COMMON_NAME, '' RQ, TO_NUMBER('') PUMP_JACK_WORKING_TIME, '' DL, TO_NUMBER('') MD_LANDED, TO_NUMBER('') TOP_MD, TO_NUMBER('') PUMP_DIAMETER, TO_NUMBER('') PUMP_EFFICIENCY, TO_NUMBER('') STROKE_LENGTH, TO_NUMBER('') STROKE_FREQUENCY, TO_NUMBER('') REVOLUTIONS, TO_NUMBER('') HYDRAULIC_HEAD, TO_NUMBER('') CASING_PRES, TO_NUMBER('') BH_PRES, TO_NUMBER('') START_FLUID_LEVEL_MD, '' WATER_QUALITY_COLOR, SUM(C.GAS_PROD_DAILY) RCQ, SUM(C.WATER_PROD_DAILY) RCS, SUM((SELECT SUM(GAS_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE < TO_DATE('20081013', 'yyyyMMdd') + 1)) LCQ, SUM((SELECT SUM(WATER_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE < TO_DATE('20081013', 'yyyyMMdd') + 1)) LCS, SUM(C.GAS_PROD_DAILY - (SELECT GAS_PROD_DAILY FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE = C.PROD_DATE - 1)) QDB, SUM(C.GAS_RELEASE_DAILY) RFKQL, N'' BZ FROM CD_WELL_SOURCE A, PC_DEV_WELL_ATTR B, PC_PRO_WELL_VOL_DAILY C, PC_PRO_WELL_STATUS_DAILY D, TEMP_WELL_MECH_ALL E, PC_ORGANIZATION_T F WHERE C.WELL_ID = A.WELL_ID(+) AND C.WELL_ID = B.WELL_ID(+) AND C.WELL_ID = D.WELL_ID(+) AND C.PROD_DATE = D.PROD_DATE(+) AND C.PROD_DATE = TO_DATE('20081013', 'yyyyMMdd') AND C.WELL_ID = E.WELL_ID(+) AND C.PROD_DATE = E.TEST_DATE(+) AND A.ORG_ID IN (SELECT ORG_ID FROM PC_ORGANIZATION START WITH ORG_ID IN ('HBwoXhrt99') CONNECT BY PRIOR ORG_ID = PARENT_ID) AND F.ORG_ID = A.ORG_ID GROUP BY F.ORG_NAME UNION ALL SELECT F.ORG_NAME ORGNAME, A.WELL_COMMON_NAME WELL_COMMON_NAME, TO_CHAR(B.PROD_DATE, 'YYYYMMDD') RQ, C.PUMP_JACK_WORKING_TIME PUMP_JACK_WORKING_TIME, DECODE(D.OIL_PROD_METHOD, '1A', D.UP_CURRENT || '/' || D.DOWN_CURRENT, D.ELEC_PUMP_CURRENT_A) DL, (SELECT DD.MD_LANDED FROM CD_WELLBORE_T AA, CD_ASSEMBLY BB, CD_ASSEMBLY_COMP CC, CD_ASSEMBLY_COMP_STATUS_T DD WHERE AA.WELL_ID = BB.WELL_ID AND AA.WELLBORE_ID = BB.WELLBORE_ID AND BB.WELL_ID = CC.WELL_ID AND BB.WELLBORE_ID = CC.WELLBORE_ID AND BB.ASSEMBLY_ID = CC.ASSEMBLY_ID AND CC.WELL_ID = DD.WELL_ID AND CC.WELLBORE_ID = DD.WELLBORE_ID AND CC.ASSEMBLY_ID = DD.ASSEMBLY_ID AND CC.ASSEMBLY_COMP_ID = DD.ASSEMBLY_COMP_ID AND AA.WELL_ID = C.WELL_ID) MD_LANDED, (SELECT TOP_MD FROM CD_COMPLETION_T T WHERE T.WELL_ID = C.WELL_ID AND ROWNUM < 2) TOP_MD, E.PUMP_DIAMETER PUMP_DIAMETER, E.PUMP_EFFICIENCY PUMP_EFFICIENCY, E.STROKE_LENGTH STROKE_LENGTH, E.STROKE_FREQUENCY STROKE_FREQUENCY, D.REVOLUTIONS REVOLUTIONS, D.HYDRAULIC_HEAD HYDRAULIC_HEAD, D.CASING_PRES CASING_PRES, D.BH_PRES BH_PRES, (SELECT Y.START_FLUID_LEVEL_MD FROM CD_PRESSURE_SURVEY T, CD_PRESSURE_AWS Y WHERE T.PRESSURE_SURVEY_ID = Y.PRESSURE_SURVEY_ID AND C.WELL_ID = T.WELL_ID) START_FLUID_LEVEL_MD, C.WATER_QUALITY_COLOR WATER_QUALITY_COLOR, C.GAS_PROD_DAILY RCQ, C.WATER_PROD_DAILY RCS, (SELECT SUM(GAS_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE < TO_DATE('20081013', 'yyyyMMdd') + 1) LCQ, (SELECT SUM(WATER_PROD_DAILY) FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE < TO_DATE('20081013', 'yyyyMMdd') + 1) LCS, C.GAS_PROD_DAILY - (SELECT GAS_PROD_DAILY FROM PC_PRO_WELL_VOL_DAILY K WHERE K.WELL_ID = C.WELL_ID AND K.PROD_DATE = C.PROD_DATE - 1) QDB, C.GAS_RELEASE_DAILY RFKQL, C.REMARKS BZ FROM CD_WELL_SOURCE A, PC_DEV_WELL_ATTR B, PC_PRO_WELL_VOL_DAILY C, PC_PRO_WELL_STATUS_DAILY D, TEMP_WELL_MECH_ALL E, PC_ORGANIZATION_T F WHERE C.WELL_ID = A.WELL_ID(+) AND C.WELL_ID = B.WELL_ID(+) AND C.WELL_ID = D.WELL_ID(+) AND C.PROD_DATE = D.PROD_DATE(+) AND C.PROD_DATE = TO_DATE('20081013', 'yyyyMMdd') AND C.WELL_ID = E.WELL_ID(+) AND C.PROD_DATE = E.TEST_DATE(+) AND A.ORG_ID IN (SELECT ORG_ID FROM PC_ORGANIZATION START WITH ORG_ID IN ('HBwoXhrt99') CONNECT BY PRIOR ORG_ID = PARENT_ID) AND F.ORG_ID = A.ORG_ID ) TEMP ORDER BY TEMP.ORGNAME, TEMP.WELL_COMMON_NAME) TTT
五、条件表达式case when then else end。语法：CASEWHEN eExpression1 THEN Value1;WHEN eExpression2 THEN Value2;WHEN eExpression3 THEN Value3;ELSE Value4;END
类似与程序里面的if else，就不过说了，看四中队例子。六、Decode()函数DECODE函数比较表达式和搜索字，如果匹配，对应的结果语法：DECODE(value,if1,then1,if2,then2,if3,then3,...,else)，表示如果value等于if1时，DECODE函数的结果返回then1,...,如果不等于任何一个if值，则返回else。比如： SELECT A.WELL_COMMON_NAME, TO_CHAR(B.PROD_DATE, 'YYYYMMDD'), C.PUMP_JACK_WORKING_TIME, decode(d.OIL_PROD_METHOD, '1A', D.UP_CURRENT || '/' || D.DOWN_CURRENT, d.ELEC_PUMP_CURRENT_A) dl, from CD_WELL_SOURCE a, PC_DEV_WELL_ATTR b, PC_PRO_WELL_VOL_DAILY c, PC_PRO_WELL_STATUS_DAILY d, TEMP_WELL_MECH_ALL e where c.Well_Id = a.Well_Id(+) and c.well_id = b.well_id(+) and c.well_id = d.well_id(+) and c.prod_date = d.prod_date(+) and c.prod_date = to_date('20081015', 'yyyyMMdd') AND c.well_id = e.well_id(+) AND c.prod_date = e.test_date(+) and a.Org_Id in ({OrgList}) order by c.well_id, c.prod_date