Shulou(Shulou.com)06/01 Report--

Psql testdb, system login user, local database, connect to testdb database

Psql-U testuser testdb, user testuser, connect to the local database testdb

Psql-U testuser-h 172.28.18.51 testdb, user testuser, connect to remote testdb database

Enumerate databases: / l

Select database: / c database name

Display table structure information: / d table name

Exit psgl:/q

Display character set: / encoding [sroot@AAEP7151 craft] # su postgres

Bash-4.1$ psql VoicePortal

Psql (9.2.14)

Type "help" for help.

VoicePortal=#\ d

Common instruction

Select pg_database_size ('VoicePortal')

SELECT Sname,2016-Sage

From Student; indicates the year of birth

Select DISTINCT Sno eliminates duplicate lines

FROM SC

Select Sname,Sdept,Sage

FROM Student

WHERE Sage NOT BETWEEN 20 AND 23; determine the range is not useful greater than less than, using between and

Selcet Sname .Sex

FROM Student

WHERE Sdept IN ('CS','MA','IS'); the selected major is in this collection

Select Sname

FROM Student

WHERE Sdept = 'CS' OR Sdept =' MA'

List the conditions with or or and

SELECT *

FROM Student

ORDER BY Grade DESC; sort ascending order is ASC descending order is DESC, note that Null is considered to be the largest, ascending order comes last, descending order comes first.

Aggregate function

SELECT COUNT (*)

FROM Sdudent

SELECT AVG (Grade)

FROM SC

WHERE Cno ='1'

Configuration file

/ var/lib/pgsql/data/postgresql.conf

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