String Operations

String functions are a set of operations that can be performed on an input string and return a new string or a numeric value. The followinf are the most common:

Operator | Description

SUBSTR | Extract and returns a substring with a predefined length starting at a specified position in a source string TRIM | Return a copy of a string that has specified characters removed from the beginning and the end of a string. LTRIM | Return a copy of a string that has specified characters removed from the beginning of a string. RTRIM | Return a copy of a string that has specified characters removed from the end of a string. LENGTH | Return the number of characters in a string or the number of bytes in a BLOB. REPLACE | Return a copy of a string with each instance of a substring replaced by another substring. UPPER | Return a copy of a string with all of the characters converted to uppercase. LOWER | Return a copy of a string with all of the characters converted to lowercase. INSTR | Find a substring in a string and returns an integer indicating the position of the first occurrence of the substring. Concatenation Operator | | | Concatenate two strings into a single string.

### INSTR .exec SELECT INSTR('SQLite String Functions','Functions') Position;

### LENGTH .exec SELECT LENGTH('SQLite');

LOWER

    SELECT
        LOWER('String Functions');

LTRIM

    SELECT 
    LTRIM(' SQLite '),
    LENGTH(' SQLite ') LengthBefore,
    LENGTH(LTRIM(' SQLite ')) LengthAfter;

RTRIM

    SELECT
    RTRIM(' SQLite '),
    LENGTH(' SQLite ') LengthBefore,
    LENGTH(RTRIM(' SQLite ')) LengthAfter;

REPLACE

    SELECT 
        REPLACE('These are string functions', 'These', 'Those');

SUBSTR

    SELECT 
        SUBSTR('SQLite String Functions', 1, 6);

TRIM

.exec   
    SELECT 
        TRIM(' SQLite ');

UPPER

    SELECT
        UPPER('String Functions');

Concatenation Operator ||

This example shows how to concatenate two strings into a single string:

    SELECT 'Concatenation ' || 'Operator';

Exercise

Use the following sentence and replace the 'strong' strings with 'sad' and return it in all uppercase

'Appear weak when you are strong, and strong when you are weak'