create table string_data (string_value varchar(15));
insert into string_data(string_value) values('12');
insert into string_data(string_value) values('2');
insert into string_data(string_value) values('21');
insert into string_data(string_value) values('ABC13');
insert into string_data(string_value) values('ABC23');
insert into string_data(string_value) values('abc23');
insert into string_data(string_value) values('abc32');
insert into string_data(string_value) values('abc13');

-- sort only numeric values, arrange alphanumeric strings in the end
SELECT * 
FROM string_data
ORDER BY CASE WHEN string_value LIKE '^[0-9]+$'
         THEN CAST(string_value as integer)
         ELSE NULLIF(regexp_replace(string_value, '\D', '9', 'g'), '')::int
         END;

-- first comes only numeric values, then alphanumeric sort
SELECT * 
FROM string_data 
ORDER BY COALESCE(SUBSTRING(string_value FROM '^(\d+)$')::INTEGER, 99999999999),
         SUBSTRING(string_value FROM '[a-zA-z_-]+'),
         COALESCE(SUBSTRING(string_value FROM '(\d+)$')::INTEGER, 0),
         string_value;
         
-- insert values like 'digitLetter': 1a, 2b, etc.
insert into string_data(string_value) values('2r');
insert into string_data(string_value) values('3f');
insert into string_data(string_value) values('1ab');
insert into string_data(string_value) values('1a');
insert into string_data(string_value) values('1ab');

-- first comes only numeric values, secondly strings started with a number, then strings with numbers in the end
SELECT * 
FROM string_data 
ORDER BY COALESCE(SUBSTRING(string_value FROM '^(\d+)$')::INTEGER, 99999999999), 
         SUBSTRING(string_value FROM '[a-zA-z_-]+'),
         COALESCE(SUBSTRING(string_value FROM '(\d+)$')::INTEGER, 0),
         string_value;

PostgreSQL online editor

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About PostgreSQL

PostgreSQL is a open source relational database system and is also knows as Postgres.

Key Features:

  • Postgres is not only free and open-source but also it is highly extensible.
  • Custom Data types and funtions from various programming languaues can be introduced and the good part is compiling entire database is not required.
  • ACID(Atomicity, Consistency, Isolation, Durability) compliant.
  • First DBMS which implemented Multi-version concurrency control (MVCC) feature.
  • It's the default database server for MacOS.
  • It supports all major operating systems like Linux, Windows, OpenBSD,FreeBSD etc.

Syntax help

1. CREATE

CREATE command is used to create a table, schema or an index.

Syntax:

         CREATE TABLE table_name (
                column1 datatype,
                column2 datatype,
                ....);

2. ALTER

ALTER command is used to add, modify or delete columns or constraints from the database table.

Syntax

ALTER TABLE Table_name ADD column_name datatype;

3. TRUNCATE:

TRUNCATE command is used to delete the data present in the table but this will not delete the table.

Syntax

TRUNCATE table table_name;

4. DROP

DROP command is used to delete the table along with its data.

Syntax

DROP TABLE table_name;

5. RENAME

RENAME command is used to rename the table name.

Syntax

ALTER TABLE table_name1 RENAME to new_table_name1;

6. INSERT

INSERT Statement is used to insert new records into the database table.

Syntax

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

7. SELECT

Select statement is used to select data from database tables.

Syntax:

SELECT column1, column2, ...
FROM table_name;

8. UPDATE

UPDATE statement is used to modify the existing values of records present in the database table.

Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

9. DELETE

DELETE statement is used to delete the existing records present in the database table.

Syntax

DELETE FROM table_name where condition;