Oracle Character Functions

A case conversion function

1. Grammar

UPPER(char)

LOWER(char)

INITCAP (char)

2. Code

1. SQL>select upper('hdfsj'),lower('AJKLH'),initcap('fdsl')from dual;
3. UPPER LOWER INIT
4. --------------
5. HDFSJ ajklh Fdsl

 

Two get substring function

1. Grammar

 

n can be omitted. When n is omitted, it means to truncate from the position of n to the end of the string.

m is 0, which means to intercept from the first letter of the string.

m is a negative number, truncated from the end of the string.

2. Code

1. SQL>select substr('afhdjks',2,3),substr('dfhskjd',2),substr('fhsjkd',-2,1)from dual;
3. SUB SUBSTR S
4. ----------
5. fhd fhskjd k

 

Three get string length function

1. Grammar

LENGTH(char)

2. Code

1. SQL>select length('asdf ')from dual;
3. LENGTH('ASDF')
4. --------------
5. 5

 

Four String Concatenation Function

1. Grammar

CONCAT(char1,char2)

Same as || operator

2. Code

1. SQL>select concat('as','cd')from dual;
3. CONC
4. ----
5. ascd
8. SQL>select'as'||'cd'from dual;
10. 'AS'
11. ----
12. ascd

 

Five remove substring function

1. Grammar

TRIM(c2 from c1): means to remove the string c2 from the string c1.

LTRIM(c1[,c2]): Remove c2 from the head of c1.

RTRIM (c1[,c2]): removes c2 from the tail of c1.

TRIM(c1): Remove leading and trailing spaces.

2. Code

1. SQL>select trim('a'from'asdjfka')from dual;
3. TRIM(
4. -----
5. sdjfk
7. SQL>select ltrim('ababa','a')from dual;
9. LTRI
10. ----
11. baba
13. SQL>select rtrim('ababaa','a')from dual;
15. RTRI
16. ----
17. abab

 

Six Replacement Functions

1. Grammar

REPLACE(char,s_string[,r_string])

Omit r_string, replace with spaces

2. Code

1. SQL>select replace('abcdea','a','A')from dual;
3. REPLAC
4. ------
5. AbcdeA
7. SQL>select replace('abcdea','a')from dual;
9. REPL
10. ----
11. bcde
13. SQL>select replace('abced','ab','A')from dual;
15. REPL
16. ----
17. Aced