Category Archives: MySQL

Importing an Excel spreadsheet in MySQL to quickly manipulate its data

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I’ve been asked to compute some data and statistics from an Excel spreadsheet containing an huge phonebook

The operations I need wasn’t very complicated, like to find and remove duplicate rows and so on, but I didn’t find any quick way to achieve those simple tasks using just Excel (or OpenOffice and LibreOffice).

Since I’m good in SQL, I decided to move this data in a MySQL database, then I wondered what’s the simplest way to obtain this result.

Excel Data Structure

My excel data is on three simple columns:

  • First Name
  • Last Name
  • Phone Number

I need to export my 20,000 rows in a .csv file.

Export XLS Data in a CSV

Using Microsoft Excel

From Excel, go in “Save As” then pick the option “Other Formats”, and from the combo box, choose Comma Delimited  CSV.

Microsoft Excel  by default creates values separated by a Comma, and the single column is not enclosed by any special char.

Using OpenOffice or LibreOffice

In OpenOffice, choose Save As and then CSV, using the default options the .csv file will have values separated by semicolon and enclosed by double quotes.

Create the MySQL table to import the CSV

It’s time to create the basic data structure in MySQL that will be able to host the data we exported from Excel. So the simple task is to generate a table with the same number of columns (and type) that will be associated to the Excel columns.

create table phonebook (first_name varchar(100), last_name varchar(100), phone_number varchar(100))

And now, the last step, importing the CSV in MySQL

Import the CSV (generated from an XLS) into MySQL table

Mysql offers a useful command for the operation of importing the CSV in a table, the command is LOAD DATA LOCAL INFILE.

And now the code in the case you exported the CSV from OpenOffice and the rows have the following structure:

“Mario”,”Rossi”,”+390123456789″

The code to load the data is:

load data local infile ‘phonebook.csv’ into table phonebook fields terminated by ‘,’ enclosed by ‘”‘ lines terminated by ‘\n’ (first_name, last_name, phone_number);

If you exported using Microsoft Office the rows have the following structure:

Mario;Rossi;+390123456789

The code to load the data is:

load data local infile 'phonebook.csv' into table phonebook fields terminated by ';' enclosed by '' lines terminated by '\n' (first_name, last_name, phone_number);

Migrate MySQL database from latin1 to utf8

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Unluckily it’s very common not to change the default charset of your MySQL server and, since the default is latin1, when someone wishes to store cyrillic or chinese character there are many problems.

The first step is to fix the MySQL installation in order to store internationalized information., so locate your my.cnf configuration file on Linux, or the my.ini on Windows boxes.

Search in the configuration file the [mysqld] section when there is the configuration of the MySQL server.

Insert the following lines and eventually remove any existing configuration option with the same name.

[mysqld]
character-set-server=utf8
default-collation=utf8_unicode_ci

The option character-set-server=utf8 tells to the server that, if not otherwise specified, the character set of the created databases, tables, column will be utf8.

utf8 columns will be able to store cyrillic or simplified chinese character, just to give you two examples.

The collation defines how alphabetical ordering will happen, in few words which is the order of the letters that we expect on ORDER BY columnName clauses.

The suffix _ci means that ordering and comparison will be case insensitive and this is the common behavior used in databases.

Be very careful, because usually programming languages (i.e. Java) have case sensitive .equals(String string) method on String class, so it’s quite common to have some mistakes caused by this incongruency.

Then look for the [client] section of your configuration file, and write this line below it.

[client]
default-character-set=utf8

This is very important because it defines the character set used by the MySQL command-line client, and that’s what will be used to migrate the data from latin1 to utf8.

Now everything is setup, restart MySQL to make sure it’s using the updated configuration, and shut-down any application that is using the database that’s going to be migrated.

First, mysqldump will create a .sql file containing all the data:

mysqldump --skip-set-charset --no-create-db –no-create-info -h hostname --protocol=TCP -P 3306 -u username -p old_database > dump.sql

The option --skip-set-charset prevents that in the dump file will be any reference to the old (and wrong) character sets. The options --no-create-db and --no-create-info are used because the new database name will be defined later.

Now the new database is going to be created: mysql -u username -p and the following SQL should be executed in the terminal:

create schema new_database;
quit

Finally the last step is to populate the brand new database with the dumped data:

mysql -u username -p new_database < dump.sql

In this way all the previous data from old_database is now stored in utf8 format in new_database.

I hope this tutorial can be useful, please ask any question or give your feedback.
Thank You.