如何在oracle中将不同的字符串格式转换成日期

Question

考虑 table1 和 table2。

table1 的 Column1 值为 'some_string Date: 00:30 05/16/2018 '

table2 的 Column2 值为 'some_string Date: 07-JUN-2018 '

现在我需要同时更新 table1 和 table2，其中要求首先从给定的字符串值中找到日期，然后将该日期转换为格式 'HH24:MI:ss MM/DD/YYYY'

这里的问题是需要更新不同服务器上的值，其中字符串值可能具有不同格式的日期。我试着写上面的查询，但它不起作用。

update table2
set column2 = 'some_string Date: '
            || to_char ((SELECT SUBSTR(column2, INSTR(column2, ':') + 1) AS date_value
                         FROM table2),
                      'HH24:MI:ss MM/DD/YYYY')
            || ' ';

Answer 1

SQL Fiddle

Oracle 11g R2 架构设置:

CREATE TABLE table1 ( column1 VARCHAR2(100) );

INSERT INTO table1 VALUES ( 'some_string Date: 00:30 05/16/2018 ' );

查询 1:

MERGE INTO table1 dst
USING (
  WITH split ( rid, prefix, dt ) AS (
    SELECT ROWID,
           SUBSTR( column1, 1, INSTR( column1, 'Date: ' ) + 5 ),
           SUBSTR( column1, INSTR( column1, 'Date: ' ) + 6 )
    FROM   table1
    WHERE  INSTR( column1, 'Date: ' ) > 0
  ),
  converted_dts ( rid, prefix, dt ) AS (
    SELECT rid,
           prefix,
           CASE
           WHEN REGEXP_LIKE( dt, '^\s*\d?\d:\d\d \d?\d([/-])\d?\d\d{1,4}\s*$' )
           THEN TO_DATE( dt, 'HH24:MI MM/DD/YYYY' )
           WHEN REGEXP_LIKE( dt, '^\s*\d?\d([\-])(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NO|DEC)\d{1-4})\s*%' )
           THEN TO_DATE( dt, 'DD-MON-YYYY' )
           END
    FROM   split
  )
  SELECT rid,
         prefix,
         TO_CHAR( dt, 'HH24:MI:ss MM/DD/YYYY' ) AS dt
  FROM   converted_dts
  WHERE  dt IS NOT NULL
) src
ON ( dst.ROWID = src.RID )
WHEN MATCHED THEN
  UPDATE
  SET column1 = prefix || dt

Results:

查询 2:

SELECT *
FROM   table1

Results:

|                               COLUMN1 |
|---------------------------------------|
| some_string Date: 00:30:00 05/16/2018 |

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