Single-line function

Simple function:

For example: Now you want letters to be capitalized. Such a function can be done using a single-line function.

Core of several.

String functions, numeric functions, date functions, conversion functions, general functions.

Requires the name of a single-line function, returns a value type, and accepts the type of the parameter.

String functions

Turn capital	String UPPER (String | Data column)
Turn lowercase	String LOWER (String | Data column)

Example:

SELECT UPPER (' Hello '), LOWER (' Hello ') from dual; Show ' Hello ' in virtual table

SELECT LOWER (ename) from EMP; Show employee names in lowercase

Use these two features to turn user information into a uniform uppercase or lowercase.

Example:

For example, enter the message ' Smith ' to output ' Smith '.

Oracle has an alternative operation that

For example:

SELECT * from &tablename;

SELECT * from EMP WHERE ename= UPPER (' &name ');

First letter uppercase, remaining letter lowercase /td>	String Initcap (String | column)
Calculation Length of string	Length (string | column)
Replaces the contents of the specified string,	String replace (String | column, content to replace, replace)
Intercept operation.	SUBSTR (string | column, intercept start index)
	substr  (string | column, intercept start index, knot Bundle index)
Remove left and right spaces	TRIM (word Character string | column)

Convert first Letter Capital Select Initcap (ename) from EMP; Calculate length Select Length ('Hello') from EMP; SELECT ename, LENGTH (ename) from EMP; SELECT ename from emp WHERE LENGTH (ename)=5; Replace operation Select Replace ('Hello World','L','_') from EMP; SELECT ename,replace (ename,'A','_') from EMP; intercept operation Select SUBSTR ('Hello World',7) from DUAL; SELECT SUBSTR ('Hello World',7,9from DUAL; The Intercept starts at 1, not 0SELECT ename,substr (ename,1,3) from EMP; First three-bit select Ename,substr (ename,length (ename)-2, LENGTH (ename)) From EMP; The three-bit removal of the left and right spaces after the name is removed select TRIM ('Helllo World') from DUAL;

Numeric functions:

Single-line function