SQL Courses

SQL - Intro to Computer Science - Harvard's CS50 (2018)

SQL Tutorial - Full Database Course for Beginners

My code

sql-code.txt

SQL online practice

SQLite online

SQL basis

SQL (Structured Query Language) is one of the languages with which we can communicate with databases. SQL is the general language, but different organisations have come up with their own dialects.

SQLite, for example, which generally follows PostgreSQL syntax, defines a specific set of supported datatypes:

• BLOB
• INTEGER
  • smallint (2 bytes)
  • integer (4 bytes)
  • bigint (8 bytes or 32 bytes )
• NUMERIC
  • boolean
  • date
  • datetime
  • numeric(scale,precision)
  • time
  • timestamp
• REAL
  • real
  • double precision
• TEXT
  • char(n)
  • varchar(n)
  • text

Most common datatypes:

• INT - whole numbers
• DECIMAL (M,N) - decimal numbers
• VARCHAR(n) - string of text