2.3. Creating a New Table
You can create a new table by specifying the table name, along with all column names and their types:
CREATE TABLE weather ( city varchar(80), temp_lo int, -- low temperature temp_hi int, -- high temperature prcp real, -- precipitation date date );
You can enter this into
psql with the line breaks.
psql will recognize that the command is not terminated until the semicolon.
White space (i.e., spaces, tabs, and newlines) can be used freely in SQL commands. That means you can type the command aligned differently than above, or even all on one line. Two dashes (“
--”) introduce comments. Whatever follows them is ignored up to the end of the line. SQL is case insensitive about key words and identifiers, except when identifiers are double-quoted to preserve the case (not done above).
varchar(80) specifies a data type that can store arbitrary character strings up to 80 characters in length.
int is the normal integer type.
real is a type for storing single precision floating-point numbers.
date should be self-explanatory. (Yes, the column of type
date is also named
date. This might be convenient or confusing — you choose.)
PostgreSQL supports the standard SQL types
interval, as well as other types of general utility and a rich set of geometric types. PostgreSQL can be customized with an arbitrary number of user-defined data types. Consequently, type names are not key words in the syntax, except where required to support special cases in the SQL standard.
The second example will store cities and their associated geographical location:
CREATE TABLE cities ( name varchar(80), location point );
point type is an example of a PostgreSQL-specific data type.