Using SELECT And UNION ALL To JOIN SQL Tables To CSV Data In MySQL

Ben Nadel merges CSV (Comma-Separated Value) data with a SQL table by generating a derived table via SELECT / UNION ALL statements in MySQL. He then uses the SQL table to augment the existing values in the CSV payload. SQL is so hot right now!

I just love SQL. I've been writing web-applications on top of relational databases (RDBMS) for a while; and, SQL always feels like a luxurious combination of structure and flexibility. Yesterday, when working with some data scientists, I had to merge a few columns from a database table into a CSV (Comma-Separated Values) file that the data scientists had created. The CSV file was fairly small; so, I ended up using the awesome power of multiple-cursors in SublimeText 3 in order to write a SQL query that converted the CSV data into a derived table that I then consumed in an INNER JOIN in MySQL.

To be clear, this is not the only way to consume CSV data in a relational database. But, I was working with a database in which I had read only permissions. As such, I couldn't load the CSV file into a "real table". Given the relatively small size of the CSV payload, what follows just felt like the appropriate level of effort.

That said, let's paint a picture of what was going on. Imagine that I had a database table called friend with the following structure:

SHOW CREATE TABLE friend;
-- Generates the following SQL statement:

CREATE TABLE `friend` (
    `id` int(11) NOT NULL,
    `name` varchar(50) NOT NULL,
    `age` int(11) NOT NULL,
    `catchPhrase` varchar(250) NOT NULL,
    PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

sql mysql

SQL stands for Structured Query Language. SQL is a scripting language expected to store, control, and inquiry information put away in social databases. The main manifestation of SQL showed up in 1974, when a gathering in IBM built up the principal model of a social database. The primary business social database was discharged by Relational Software later turning out to be Oracle.

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