| NO | 问题点 | Oracle | PostgreSQL |
| 1 | DUAL | SELECT 1+1 FROM DUAL | SELECT 1+1 或者 CREATE VIEW dual AS SELECT \'X\'::VARCHAR(1) AS DUMMY 再 SELECT 1+1 FROM DUAL |
| 2 | NEXTVAL | SELECT A_TABLE_SEQUENCE.NEXTVAL FROM DUAL |
SELECT NEXTVAL(\'A_TABLE_SEQUENCE\') FROM DUAL |
| 3 | ROWNUM | ①SELECT * FROM AGE_TYPE WHERE ROWNUM<=5 |
①SELECT * FROM AGE_TYPE LIMIT 5 OFFSET 0 |
| ②SELECT * FROM AGE_TYPE WHERE CODE IS NOT NULL AND ROWNUM<=5 ORDER BY CODE DESC |
②SELECT * FROM AGE_TYPE WHERE CODE IS NOT NULL ORDER BY CODE DESC LIMIT 5 OFFSET 0 |
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| 4 | (+) | ①SELECT * FROM A_TABLE A , B_TABLE B WHERE A.ID(+)=B.ID |
①SELECT * FROM A_TABLE A RIGHT OUTER JOIN B_TABLE B ON A.ID=B.ID |
| ②SELECT * FROM A_TABLE A , B_TABLE B WHERE A.ID(+)=B.ID AND A.COL1=\'COL1_VALUE\' |
②SELECT * FROM A_TABLE A RIGHT OUTER JOIN B_TABLE B ON A.ID=B.ID AND A.COL1=\'COL1_VALUE\' |
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| ③SELECT * FROM A_TABLE A, B_TABLE B,C_TABLE C,D_TABLE D WHERE A.ID=B.ID(+) AND A.ID=C.ID(+) AND A.COL1=D.COL1 |
③SELECT * FROM (A_TABLE A LEFT OUTER JOIN B_TABLE B ON A.ID=B.ID) LEFT OUTER JOIN C_TABLE C ON A.ID=C.ID,D_TABLE D WHERE A.COL1=D.COL1 |
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| ④!!! SELECT * FROM A_TABLE A WHERE A.COL1(+)=0 AND A.COL2(+) =\'A_VALUE2\' |
④!!! SELECT * FROM A_TABLE A WHERE A.COL1=0 AND A.COL2=\'A_VALUE2\' (A.COL2=\'A_VALUE2\' OR A.COL2 IS NULL) |
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| 5 | AS | SELECT A.COL1 A_COL1, A.COL2 A_COL2 FROM A_TABLE A |
SELECT A.COL1 AS A_COL1, A.COL2 AS A_COL2 FROM A_TABLE A |
| 6 | NVL | SELECT NVL(SUM(VALUE11),0) FS_VALUE1, NVL(SUM(VALUE21),0) FS_VALUE2 FROM FIELD_SUM |
SELECT COALESCE(SUM(VALUE11),0) AS FS_VALUE1, COALESCE(SUM(VALUE21),0) AS FS_VALUE2 FROM FIELD_SUM |
| 7 | TO_ NUMBER |
SELECT COL1 FROM A_TABLE ORDER BY TO_NUMBER(COL1) |
SELECT COL1 FROM A_TABLE ORDER BY TO_NUMBER(COL1,999999) [注：\'999999\' ---- 6位数为COL1字段的长度] |
| 8 | DECODE | SELECT DECODE(ENDFLAG,\'1\',\'A\',\'B\') ENDFLAG FROM TEST |
SELECT (CASE ENDFLAG WHEN \'1\' THEN \'A\' ELSE \'B\' END) AS ENDFLAG FROM TEST |
| 9 | 时间 问题 |
UPDATE A_TABLE SET ENTREDATE=SYSDATE |
UPDATE A_TABLE SET ENTREDATE=TO_TIMESTAMP(CURRENT_TIMESTAMP,\'YYYY-MM-DD HH24:MI:SS\') 或者 UPDATE A_TABLE SET ENTREDATE=CURRENT_TIMESTAMP |
| SELECT TO_DATE(\'20010203\',\'YYYY-MM-DD\') AS DAY FROM DUAL |
SELECT TO_DATE(\'20010203\',\'YYYYMMDD\') AS DAY FROM DUAL SELECT TO_DATE(\'20010203\',\'YYYY-MM-DD\') AS DAY FROM DUAL |
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| SELECT TO_DATE(SYSDATE,\'YYYY-MM-DD\') AS DAY FROM DUAL |
SELECT TO_DATE(CURRENT_DATE,\'YYYY-MM-DD\') AS DAY FROM DUAL |
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| SELECT TO_DATE(SYSDATE,\'YYYY/MM/DD\') AS DAY FROM DUAL |
SELECT TO_DATE(CURRENT_DATE,\'YYYY/MM/DD\') AS DAY FROM DUAL |
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| 10 | || | SELECT NULL||\'-\'||NULL AS VALUES1 FROM DUAL |
SELECT COALESCE(NULL,\'\')||\'-\'||COALESCE(NULL,\'\') AS VALUES1 FROM DUAL FROM DUAL |
| 11 | aggregate | SELECT ROUND(AVG(SUM(BASICCNT1))) BASICCNT FROM ACCESS_INFO_SUM1_V WHERE YEARCODE BETWEEN \'200305\' AND \'200505\' GROUP BY SCCODE |
SELECT ROUND(AVG(AIV.BASICCNT)) AS BASICCNT FROM (SELECT SUM(BASICCNT1) AS BASICCNT FROM ACCESS_INFO_SUM1_V WHERE YEARCODE BETWEEN \'200305\' AND \'200505\' GROUP BY sccode ) AIV |
| 12 | 「"」 | ①SELECT LENGTH(\'\') AS VALUE1 FROM DUAL [Result]VALUE1=NULL |
①SELECT LENGTH(\'\') AS VALUE1 FROM DUAL [Result]VALUE1=0 |
| ②SELECT TO_DATE(\'\',\'YYYYMMDD\') AS VALUE2 FROM DUAL [Result]VALUE2=NULL |
②SELECT TO_DATE(\'\',\'YYYYMMDD\') AS VALUE2 FROM DUAL [Result]VALUE2=0001-01-01 BC |
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| ③SELECT TO_NUMBER(\'\',1) AS VALUE3 FROM DUAL [Result]VALUE3=NULL |
③SELECT TO_NUMBER(\'\',1) AS VALUE3 FROM DUAL [Result]不能执行 |
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| ④INSERT INTO TEST(VALUE4)VALUES(\'\') [Result]VALUE4=NULL (注：VALUE3字段为数值类型) |
④INSERT INTO TEST(VALUE4)VALUES(\'\') [Result]VALUE4=0 (注：VALUE4字段为数值类型) |
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| ⑤INSERT INTO TEST(VALUE5)VALUES(\'\') [Result]VALUE5=NULL (注：VALUE5字段为字符类型) |
⑤INSERT INTO TEST(VALUE5)VALUES(\'\') [Result]VALUE5=\'\' (注：VALUE5字段为字符类型,结果为长度为零的字符串) |
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| ⑥INSERT INTO TEST(VALUE6)VALUES(TO_DATE(\'\',\'YYYYMMDD\')) [Result]VALUE6=NULL (注：VALUE6字段为时间类型) |
⑥INSERT INTO TEST(VALUE6)VALUES(TO_DATE(\'\',\'YYYYMMDD\')) [Result]VALUE6=0001-01-01 BC (注：VALUE7字段为时间类型) |
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| 13 | CEIL | SELECT CEIL(SYSDATE - TO_DATE(\'20051027 14:56:10\',\'YYYYMMDD HH24:MI:SS\')) AS DAYS FROM DUAL |
SELECT EXTRACT(DAY FROM (TO_TIMESTAMP(CURRENT_TIMESTAMP,\'YYYY-MM-DD-HH24-MI-SS\') -TO_TIMESTAMP(\'2005-10-27 14:56:10\',\'YYYY-MM-DD-HH24-MI-SS\') ))+1 AS DAYS FROM DUAL |
| 14 | NULLIF | 无NULLIF函数 | SELECT NULLIF(VALUE1,VALUE2) AS COL1 FROM DUAL [注]当VALUE1=VALUE2时，COL1=NULL |
| 15 | CONCAT | CONCAT(CHAR,CHAR) | 创建函数来解决 CREATE FUNCTION CONCAT(CHAR,CHAR) RETURNS CHAR AS \'SELECT $1 || $2\' LANGUAGE \'sql\'; |
| 16 | ADD_ MONTHS |
add_months(date, int) | 创建函数来解决 CREATE FUNCTION add_months(date, int) RETURNS date AS \'SELECT ($1 + ( $2::text || \'\'months\'\')::interval)::date;\' LANGUAGE \'sql\' |
| 17 | LAST _DAY |
LAST_DAY(DATE) | 创建函数来解决 CREATE FUNCTION LAST_DAY(DATE) RETURNS DATE AS \'SELECT date(substr(text($1 + interval(\'\'1 month\'\')),1,7)||\'\'-01\'\')-1\' LANGUAGE \'sql\'; |
| 18 | MONTHS _BETWEEN |
MONTH_BETWEEN(DATA,DATA) | 创建函数来解决 CREATE FUNCTION MONTH_BETWEEN(DATA,DATA) RETURNS NUMERIC AS \'SELECT to_number((date($1)- date($2)),\'\'999999999\'\')/31\' LANGUAGE \'sql\'; |
| 19 | GRE~ ATEST |
GREATEST (LEAST) | 创建函数来解决 CREATE OR REPLACE FUNCTION GREATEST(TEXT[]) RETURNS TEXT AS \' DECLARE ARRY ALIAS FOR $1; GREATEST TEXT; BEGIN GREATEST := ARRY[1]; FOR I IN 1 .. ARRAY_UPPER(ARRY,1) LOOP IF ARRY[I] > GREATEST THEN GREATEST := ARRY[I]; END IF; END LOOP; RETURN GREATEST; END; \' LANGUAGE \'PLPGSQL\'; SELECT GREATEST( ARRAY[\'HARRY\',\'HARRIOT\',\'HAROLD\']) AS "Greatest"; |
| 20 | BITAND | BITAND(int,int) | SELECT 値 & 値; |
| 21 | 子条件 | 在FROM子条件中字段须有列名， 处理方法用AS +别名 |
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| 22 | MINUS | MINUS | 以EXCEPT来替代 |
| 23 | BIN_ TO_ NUM |
SELECT BIN_TO_NUM(1,0,1,0) AS VALUE1 FROM DUAL | SELECT CAST(B\'1010\' AS INTEGER) AS VALUE1 |
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