![]() ![]() Need hosting for your next web application or WordPress site? I highly recommend Hostinger and use them to host my niche bass fishing site.Get your brand, product, or service the attention it deserves with affordable classified ad placement in the OpenLampTech newsletter.Let’s both save money on the plans offered. Starting a blog? I use WordPress for the Digital Owl’s Prose blog.My opinions are my own.Ĭheck out this article from the OpenLampTech publication page, Book Recommendation – SQL Antipatterns. Like always, just because you can do something doesn’t mean you should. Your particular goals and needs may vary. Please check code below: DROP TABLE `customers` Īnd table customers in now removed from the data base.Josh Otwell has a passion to grow as a PHP Developer, SQL expert, and technical blogger/writer.ĭisclaimer: The majority of examples in this post, are performed in a personal development/learning workstation environment and should not be considered production quality or ready. This is the easier query in this article. For example, we decided that we don’t need any more this table and we want to remove it from our data base. I will show now how to delete existing table in MySQL. In our case we must change existing “description” column in MySQL table, so our query will look like: ALTER TABLE `customers`Ĭheck on images how to change existing table in PhpMyAdmin using query: MySQL changing existing column in table The syntax of this query is: ALTER TABLE `table_name`ĬHANGE `column_name` `column_name` TYPE(LENGTH) ADDITIONAL_ATTRIBUTES It means we want to change type of column from VARCHAR into “TEXT”. It is quite ease.įor example, we decided that last column in “customers” table must be longer. So now we know how to create new table in MySQL, how to add new column and now I will show how to change existing column in MySQL table. OK – I hope it was easy □ Let’s go to next point. Please check it on images which shows how to add new column to table in PhpMyAdmin using queries: MySQL add new column to existing table In my example, I want to place new MySQL table’s column just after “name” column. The only one new thing is that on the end of query we have to write where new column should be placed. Then we write ADD COLUMN in the same syntax as we used for table creation (above – step 1). We user ALTER TABLE command to modify an exiting MySQL table. ![]() ![]() In our example it will looks like below: ALTER TABLE customersĪDD COLUMN currency VARCHAR(3) NOT NULL AFTER `name` To add a new column to existing MySQL table we must use following syntax: ALTER TABLE table_nameĪDD COLUMN new_column_name TYPE(LENGTH) ADDITIONAL_ATTRIBUTES This column should contain currency (GBP, EUR, USD…) assigned to each user. We have our “customers” table, but we realized, that we need one more column there. OK so now creating new table should be easy □ Add new column in MySQL existing table “description” – column can contain strings values with max 30 length Ĭheck how creating new table in MySQL looks in PhpMyAdmin on images: MySQL command MySQL command New customers table.“age” – only integer numbers max length 3, this field can’t be empty.“name” – column can contain strings values with max 30 length and it can’t be empty.“id” – only integer numbers max length 6, values have to be equal or greater than 0, this field can’t be empty, is a key field, which identify rows in table and increase by 1 when new row is added.Using simple words, we create new MySQL table “customers”, with following 4 fields: AUTO_INCREMENT – data base engine will increase value of that field by 1 for each new added row.PRIMARY KEY – Make unique order for rows in a table,.You can’t leave this field empty (null = empty), NOT NULL – data is required for that field.UNSIGNED – column can contain only numbers equal or greater than zero,.I explained below used attributes in my example: what is allowed in column or if column has an important task to do. This what I called “ADDITION_ATTRIBUTES” is some kind of specification and it describes eg. Id INT(6) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,įirst we declare column name (like above: id, name, age, description) and its length in bracket eg. Code looks like below, I will explain it further. We need as columns: unique ID for each customer, her/his name, age and some description. We are creating new table in MySQL which will contain customers data. To create new table in MySQL we need to follow code like below: CREATE TABLE new_table_name (Ĭolumn_name TYPE(LENGTH) ADDITIONAL_ATTRIBUTES,īut it could look quite mysterious, so take a look below on real example. ![]()
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