Databases Archives - Ian Carnaghan
How to increase the length of a character varying datatype in Postgres without data loss
Run the following command: alter table TABLE_NAME alter column COLUMN_NAME type character varying(120); This will extend the character varying column field size to 120. Remember...
How to copy data from one table to another using pgsql
If you need to copy data from one table (table_a) into another table (table_b) using pgsql. There are 2...
How to copy a columns data from one table into a column in another table using PostGreSQL
How to copy a columns data from one table into a column in another table using PostgreSQL? Eg. name columns data from the users table into namecolumn in the new_users table. Execute the query below with different column names and table names and...
How to check what version of PostgreSQL your running
Run the following query: SELECT version(); The result will look as below: version ————————————————————————————————— PostgreSQL 8.3.7 on i486-pc-linux-gnu, compiled...
How to create a backup of a PostgreSQL database to a SQL file
How to create a backup of a PostgreSQL database to a sql file? This sql file then can be used to restore the database on a later stage. Follow the steps below...
Eliminating duplicate rows from result-set using PostgreSQL
Use the DISTINCT ON keyword in your query To do a case-insensitive search do the following query SELECT DISTINCT ON(upper(surname)) surname FROM employees ORDER BY upper(surname) This will...
How to import a CSV file into a PostgreSQL database table
Type in the following command in postgres using the command line: copy products from ‘/home/user/products.csv’ using delimiters ‘,’ products = (Database Table) ‘/home/user/products.csv‘ = (Location of...
How to export data to a CSV file from a PostgreSQL database together with table headings
Type in the following command in postgres using the command line: copy products to ‘/home/user/products.csv’ delimiters ‘,’ CSV HEADER products = (Database Table) ‘/home/user/products.csv‘ = (Location...
How to export data to a CSV file from a PostgreSQL database
Type in the following command in postgres using the command line: copy products to ‘/home/user/products.csv’ delimiters ‘,’ products = (Database Table) ‘/home/user/products.csv‘ = (Location where to...
