Notes to myself
I have been reviewing database to refresh my knowledge of SQL. I have used both SQLite and PostgreSQL before. For my recent project What to Watch I’ve used PostgreSQL as I was planning to deploy it Heroku. Here are some notes to myself about PostgreSQL.
What is PostgreSQL?
PostgreSQL is a general-purpose object-relational database management system.
The full list of Data Types can be found here Data Type full list. I will only list some main PostgreSQL data types such as Character, Number, Serial, Temporal Data, Boolean.
Here are some examples:
PostgreSQL offers three character data types:
CHAR(n) - fixed-length character strings VARCHAR(n) - Variable-length strings TEXT - Strings of any length(unlimited length character string)
PostgreSQL supports two distinct types of numbers,
Floating-point numbers. Each of these type has several subtypes.
SMALLINT(Small integer) - 2-byte signed integer that has a range from -32,768 to 32,767. INT(Integer) - 4-byte integer that has a range from -2,147,483,648 to 2,147,483,647. Serial - It's the same as integer except that PostgreSQL will automatically generate and populate values into the SERIAL column.
Floating-Point Number subtypes
In PostgreSQL there are three main types of floating-point numbers:
float(n) - is a floating-point number whose precision - is at least, n, up to a maximum of 8 bytes. real - is a 4-byte floating-point number. numeric or numeric(p,s): is a real number with p digits with s number after the decimal point. The numeric(p,s) is the exact number
Temporal Data Types
Temporal data types store time-related information: Data, time, timestamp, interval, timestamptz
Boolean data type includes TRUE, FLASE, NULL. Postgres is not limited by
false values into boolean columns. In boolean columns
we can insert values like
f and they will be interpreted as
In my next post, I will give some instances with the data types listed above.