什么是等价的?=在Oracle正则表达式中

REGEXP_SUBSTR('DASOMETHINGBLK','DA(.*)BLK', 1,1,NULL,1)
               --                           ^ ^      ^
               --starting from first, find first     1st match bet'n ()

http://sqlfiddle.com/#!4/97eade/967

LIKE

CREATE TABLE table_name ( id, column_name ) AS
  SELECT 1, 'dablk' FROM DUAL UNION ALL
  SELECT 2, 'datestblk' FROM DUAL UNION ALL
  SELECT 3, 'atestblk' FROM DUAL UNION ALL
  SELECT 4, 'datestbl' FROM DUAL UNION ALL
  SELECT 5, 'dadatestblkblk' FROM DUAL;

da blk

SELECT id,
       SUBSTR( column_name, 3, LENGTH( column_name ) - 5 )
FROM   table_name
WHERE  column_name LIKE 'da%blk';

ID | SUBSTR(COLUMN_NAME,3,LENGTH(COLUMN_NAME)-5)
---|--------------------------------------------
 1 | (null)
 2 | test
 5 | datestblk

a b

SELECT id,
       SUBSTR(
         column_name,
         first_a + 1,
         last_b - first_a - 1
       ) AS value
FROM   (
  SELECT t.*,
         INSTR( column_name, 'a' ) AS first_a,
         INSTR( column_name, 'b', -1 ) AS last_b
  FROM   table_name t
  WHERE  column_name LIKE '%a%b%'
)

ID | VALUE    
---|----------
 1 | (null)
 2 | test     
 3 | test     
 4 | test     
 5 | datestblk

here