t3 concentrator

relatively troublesome. Using exp and IMP has many restrictions. Using copy is relatively simple and quick.2. You do not need to create a database chain, as long as the remote database is configured in the local tnsnames. ora, you can directly access the database. Easy to operate. It also supports copy from the local database to the local database.3. The syntax is flexible. The name of the target table does not match the name in the query statement, and there are multiple data processing method

'Then 1 else 0 end) as UML pass percentage, Sum (case when C # = '004 'then score else 0 end)/sum (Case C # When '004 'then 1 else 0 end) as database average score, 100 * sum (case when C # = '004 'and score> = 60 then 1 else 0 end) /sum (case when C # = '004 'Then 1 else 0 end) as database pass percentageFrom SC21. query the average scores of different courses taught by different teachers from high to low.Select max (Z. T #) as instructor ID, max (Z. tname) as instructor name, C. C # As course

(); W2.start (); W3.start (); }}Example two: Packagecom.yyx.test;//using the Runnable interface method, the ticketing/** This program has a thread security issue: When printing tickets, there will be a heavy ticket, the wrong ticket*/classWindow1ImplementsRunnable {intTicket = 100; Public voidrun () { while(true) { if(Ticket > 0) { Try{Thread.Sleep (10); } Catch(interruptedexception e) {e.printstacktrace (); } System.out.println (Thread.CurrentThread (). Get

MySQL uses nested loop algorithms to implement joins between multiple tables. nested-loop Join Algorithms A simple nested loop join (NLJ) algorithm that loops through rows from the first table, takes each row, and loops through the next table in the join. This process repeats many times until the remaining tables are joined.Suppose the table T1, T2, and T3 join with the following join types: Table Join Type T1 range T2 ref

1: Copy Code code as follows: var MT = []; var index = 0; function Initialize_generator (seed) { Mt[0] = seed; for (var i = 1; i Mt[i] = 0xFFFFFFFF (0x6c078965 * (mt[i-1) ^ (mt[i-1] >>)) + i); } } function Generate_numbers () { for (var i = 0; i var y = (Mt[i] 0x80000000) + (mt[(i + 1)% 624] 0x7fffffff); Mt[i] = mt[(i + 397)% 624] ^ (y >> 1); if (y% 2!= 0) { Mt[i] ^= 0x9908b0df; } } } function Extract_number () { if (index = = 0) { Generate_numbers (); } var y

variables are defined within the class. Even though variable definitions abound in the middle of the definition of a method, those variables are initialized before any method is called-even before the builder calls. For example: : Orderofinitialization.java //demonstrates initialization order. When the constructor are called, to create a //Tagged object, you'll have a message: class Tag { tag (int marker ) { System.out.println ("+ marker +)"); } Class Card { tag T1 = new

When we use with, Oracle may convert the results in with into a temporary table. This is only possible, as the CBO will infer.Inline is not converted to a temporary table. Materialize is forced into a temporary table.Manufacturing datadrop table Test1 Purge;drop table Test2 purge;drop table Test3 Purge;CREATE TABLE Test1 as SELECT * from Dba_objects;CREATE TABLE Test2 as SELECT * from User_objects;CREATE TABLE Test3 as SELECT * from Dba_objects;exec dbms_stats.gather_table_stats (user, ' test1 '

character set, up to 65535/(128*3) = 170 characters.three-TestEnvironment Server Version:5.6.26-74.0-log Percona Servermysql> CREATE TABLE T1(id int not NULL auto_increment primary key,-Name varchar (10)) Engine=innodb default charset=utf8mb4;Query OK, 0 rows affected (0.01 sec)Mysql> CREATE TABLE T2(id int not NULL auto_increment primary key,-Name varchar (10)) Engine=innodb default Charset=utf8;Query OK, 0 rows affected (0.01 sec)mysql> CREATE TABLE T3