в 13:45, 26 мая 2010

2010-05-26T13:45:19Z

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2010-05-26T10:02:06Z

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==Group the letters "ir" together by putting them in parentheses==



<source lang="sql">

SQL> create table TestTable(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 Description VARCHAR2(30 BYTE)
4 )
5 /
Table created.
SQL>
SQL>
SQL> insert into TestTable (ID, Description) values("1","1234 5th Street");
1 row created.
SQL> insert into TestTable (ID, Description) values("2","1 Culloden Street");
1 row created.
SQL> insert into TestTable (ID, Description) values("3","1234 Road");
1 row created.
SQL> insert into TestTable (ID, Description) values("4","33 Thrid Road");
1 row created.
SQL> insert into TestTable (ID, Description) values("5","One than another");
1 row created.
SQL> insert into TestTable (ID, Description) values("6","2003 Movie");
1 row created.
SQL> insert into TestTable (ID, Description) values("7","Start With Letters");
1 row created.
SQL>
SQL> select * from TestTable;
ID DESCRIPTION
---- ------------------------------
1 1234 5th Street
2 1 Culloden Street
3 1234 Road
4 33 Thrid Road
5 One than another
6 2003 Movie
7 Start With Letters
7 rows selected.
SQL>
SQL> --Group the letters "ir" together by putting them in parentheses and then parenthesizing the suffix using alternation:
SQL>
SQL> SELECT description, REGEXP_SUBSTR(description,"(ir)(d|s)") FROM testTable;
DESCRIPTION REGEXP_SUBSTR(DESCRIPTION,"(IR
------------------------------ ------------------------------
1234 5th Street
1 Culloden Street
1234 Road
33 Thrid Road
One than another
2003 Movie
Start With Letters
7 rows selected.
SQL>
SQL>
SQL>
SQL> drop table TestTable;
Table dropped.
SQL>
SQL>

</source>

==Parenthesize both expressions==



<source lang="sql">

SQL> create table TestTable(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 Description VARCHAR2(30 BYTE)
4 )
5 /
Table created.
SQL>
SQL>
SQL> insert into TestTable (ID, Description) values("1","1234 5th Street");
1 row created.
SQL> insert into TestTable (ID, Description) values("2","1 Culloden Street");
1 row created.
SQL> insert into TestTable (ID, Description) values("3","1234 Road");
1 row created.
SQL> insert into TestTable (ID, Description) values("4","33 Thrid Road");
1 row created.
SQL> insert into TestTable (ID, Description) values("5","One than another");
1 row created.
SQL> insert into TestTable (ID, Description) values("6","2003 Movie");
1 row created.
SQL> insert into TestTable (ID, Description) values("7","Start With Letters");
1 row created.
SQL>
SQL> select * from TestTable;
ID DESCRIPTION
---- ------------------------------
1 1234 5th Street
2 1 Culloden Street
3 1234 Road
4 33 Thrid Road
5 One than another
6 2003 Movie
7 Start With Letters
7 rows selected.
SQL>
SQL>
SQL>
SQL> -- Parenthesize both expressions
SQL>
SQL> SELECT description, REGEXP_SUBSTR(description,"(ir)d|s") FROM testTable;
DESCRIPTION REGEXP_SUBSTR(DESCRIPTION,"(IR
------------------------------ ------------------------------
1234 5th Street
1 Culloden Street
1234 Road
33 Thrid Road
One than another
2003 Movie
Start With Letters s
7 rows selected.
SQL>
SQL>
SQL> drop table TestTable;
Table dropped.
SQL>
SQL>
SQL>

</source>

==REGEXP_SUBSTR("Yababa dababa do","(ab)")==



<source lang="sql">

SQL> --Backreference
SQL>
SQL>
SQL> SELECT REGEXP_SUBSTR("Yababa dababa do","(ab)") FROM dual;
RE
--
ab
SQL>

</source>

==REGEXP_SUBSTR("Yababa dababa do","(ab)\1"), backreference option==



<source lang="sql">

SQL> --pattern is matched. If we use the backreference option, the query looks like this:
SQL>
SQL> SELECT REGEXP_SUBSTR("Yababa dababa do","(ab)\1")FROM dual;
REGE
----
abab
SQL>

</source>

==Using backreference: REGEXP_REPLACE("H1234 H4321 H2345","(.*) (.*) (.*)","\3, \2 \1")==



<source lang="sql">

SQL> --For a better example of using backreference, let"s suppose we wanted to convert a
name in the form "first middle last" into the "last, middle first" format. Consider this command:
SQL>
SQL> SELECT REGEXP_REPLACE("H1234 H4321 H2345","(.*) (.*) (.*)","\3, \2 \1")FROM dual;
REGEXP_REPLACE("H1
------------------
H2345, H4321 H1234
SQL>
SQL>

</source>

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в 13:45, 26 мая 2010

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