Four kinds of databases, the method of taking random records

Data | database | random
Mysql:select * FROM TableName the ORDER by rand () limit 10sqlserver:select the top of the TableName Order by NEWID ()

ORACLE: A way to use DBMS random value


Sql> Select *from (select *from t Order by Dbms_random.value) where rownum<10;

A----------39 101 134 5 83 97 96 140 81

9 rows have been selected.

Sql> Select *from (select *from t Order by Dbms_random.value) where rownum<10;

A----------27 118 141 103 128 10 142 68 74 Some say it's an efficiency The worst way to ask for a better solution than this!

ACCESS (i):
Yourstr= "*1*3*4*6*12* ..." "sql=" select top * Form Yourdb where InStr (' * ' &id& ' * ', ' &yourstr& ') < >0
ACCESS (ii):
<%   n=10     ' Take any 10 records    Set rs = server. CreateObject ("Adodb.recordset")       sql = "SELECT * FROM table"        rs.open sql,conn,1,1      count=rs.recordcount   ' Total Records       if Count<>empty then          randomize               for i = 1 to n        ' cycle n times            Num=fix ( rnd*count) ' num is the number of randomly generated rows of records, with fix () so that it is not greater than the count value.            rs.move num     ' move to change random line             Response.Write Rs (0)    ' out of this record          rs.movefirst     ' Don't forget to move the pointer to the first one         next      end IF       rs.close   Set rs = nothing%>



Sql> Select *from (select *from t Order by Dbms_random.value) where rownum<10;

A----------39 101 134 5 83 97 96 140 81

9 rows have been selected.

Sql> Select *from (select *from t Order by Dbms_random.value) where rownum<10;

A----------27 118 141 103 128 10 142 68 74 Some say it's an efficiency The worst way to ask for a better solution than this!

ACCESS (i):
Yourstr= "*1*3*4*6*12* ..." "sql=" select top * Form Yourdb where InStr (' * ' &id& ' * ', ' &yourstr& ') < >0
ACCESS (ii):
<%   n=10     ' Take any 10 records    Set rs = server. CreateObject ("Adodb.recordset")       sql = "SELECT * FROM table"        rs.open sql,conn,1,1      count=rs.recordcount   ' Total Records       if Count<>empty then          randomize               for i = 1 to n        ' cycle n times            Num=fix ( rnd*count) ' num is the number of randomly generated rows of records, with fix () so that it is not greater than the count value.            rs.move num     ' move to change random line             Response.Write Rs (0)    ' out of this record          rs.movefirst     ' Don't forget to move the pointer to the first one         next      end IF       rs.close   Set rs = nothing%>