the SELECT * from the Tab; // get all the table names in the current database user
the SELECT sys_guid () , UserName from TESTLIKUI; // get the GUID of
the SELECT sys_guid () AS " unique identification " , UserName AS " username " , Password AS pwd from TESTLIKUI; // the GUID of after as an alias, sys_guid temporary database created for
the SELECT DISTINCT (password) as pwd from TESTLIKUI;
the SELECT * from TESTLIKUI the WHERE AGEThe BETWEEN 20 the AND 30 // acquired data age 20-30, including 20 and 30 themselves
SELECT ABS (Age) from testlikui; // ABS takes the absolute value
SELECT username || ' + ' || Age AS the infos from testlikui; / / || connector, with the age and the username + connected, output
SELECT Lower (username) from testlikui; // username in lowercase output, Upper uppercase output
SELECT CreateTime, NEXT_DAY (CreateTime, ' Wednesday ' )from testlikui; // the date createtime, access to future first Wednesday of the date (for the weekend, " Sunday " Sunday, the database does not recognize)
the SELECT * the FROM testlikui // SOUNDEX function returns a string representation of the argument in the speech, soundex consider a similar pronunciation character syllables, pronunciation so that the string comparison rather than comparing the letters,
the WHERE SOUNDEX (username) = SOUNDEX ( ' to ' ); // with the same pronunciation of some comparison (or similar), but different spelling words are very useful.
SELECT username, VSIZE (username), length (username), // Although there are "fetch length", butLENGTH function result is "How many characters", VSIZE result is "how many bytes "
CreateTime, the TO_CHAR (CreateTime, ' yyyy-mm-dd HH: mm: mm ' ) // The former is mainly the date, time, or the number of conversion text, where we put into the fixed date format of the output
from testlikui;
SELECT username, substr (username, 2 , 2 ), // target field username, beginning from the second interception, the interception of a string of two
substr ( username, 2 ), // from the second start capturing, intercepts all back
substr (username, - . 1), // reverse interception, the interception of the first countdown, all taken back
substr (username, - 2 ) // reverse taken, the first one taken from the reciprocal, back intercepts all
substr (username, - . 4 , 2 ) , // reverse interception, the interception of the reciprocal position 4, taken back two
substr (username, - 4 , . 5 ) // reverse taken, taken from fourth countdown, although taken back in claim 5, but actually, only 4, taken on all (four)
from testlikui
Note:When only two parameters; whether it is positive or negative a few a few, are taken from the beginning who began intercepting all.
// rownum pseudo column is set after acquiring a query result to a plus (a plus obtain a record rownum)
SELECT * from ( SELECT * from testlikui WHERE Age = 100 ) WHERE rownum = . 1 ; // Get age 100 , the first data
select * from ( select * from testlikui WHERE Age = 100 Order by username desc) WHERE rownum = . 1 ; // Get age 100, a first array of data names flashback
select* From testlikui WHERE Age = 100 and rownum <= 2 ; // Get age 100, the first data
SELECT * from testlikui WHERE username like ' %% male ' ; // fuzzy search, with "positive" data
SELECT * from testlikui the WHERE username like ' t_ ' ; // query, the name starts with t and followed by only one character
