0:00structured query language sql or sql for
0:03short is the gold standard language for
0:06communicating with relational database
0:08management systems you've likely heard
0:09of databases like mysql
0:11postgres microsoft sql server and oracle
0:14all of which are based on sql with their
0:16own little variations
0:17it was initially developed in the early
0:1970s to mutate and retrieve data from
0:22ibm's system r database by 1986
0:25it was standardized into the syntax that
0:27remains extremely popular in technical
0:29applications today a relational database
0:31organizes data into tables
0:33kind of like an excel spreadsheet where
0:35columns contain attributes or types of
0:37data
0:37while each row represents an individual
0:39record or data point with its own unique
0:42id
0:42known as a primary key we can establish
0:44relationships between data points
0:46by taking the unique id from one row and
0:48storing it on a different row in a
0:50different table
0:51in a special column known as a foreign
0:53key in the teams table the team id
0:55is the primary key but in the players
0:57table it's the foreign key
0:59and what that data structure tells us is
1:01that a player belongs to one team
1:03while a team can have many players what
1:05we've done here
1:06is structured our data in its smallest
1:08normal form to eliminate duplication and
1:11redundancy
1:12now the role of sql is not only to read
1:15create
1:15update and delete data but also to join
1:18data together
1:19based on the relationships embedded
1:20within it the syntax
1:22is comprised of several key parts if we
1:24zoom all the way out
1:25we have a statement or a piece of code
1:27that does something
1:28like reads or writes to the database
1:30within a statement we have a variety of
1:32keywords that can manipulate the
1:34database
1:35select can be used to make a query for
1:37the columns that you want
1:38from a table the column and table names
1:41are known as
1:42identifiers but we may not want every
1:44row in the table so we filter the
1:45results with the where keyword to only
1:47include records that meet a certain
1:49condition
1:49it's like looping over every row in the
1:51table and only returning rows in the
1:53query where the predicate evaluates to
1:55true
1:55then we might use the join keyword to
1:57connect data from an entirely different
1:59table
1:59by matching the primary key on this
2:01table to the foreign key on another
2:03table
2:04what we've created is a collection of
2:05clauses that make up
2:07a full sql statement we can now go and
2:09execute this code on the hundreds of
2:11different databases that support
2:12sql this has been structured query
2:14language in 100 seconds
2:16like and subscribe if you want to see a
2:18full sql tutorial
2:19thanks for watching and i will see you
2:21in the next one