decode function

ImportSocketImportSysport=51423Host="localhost"Data=b"x"*10485760#在字符串前加 B is the string into the bytes class. sock=Socket.socket (Socket.af_inet,socket. Sock_stream) Sock.connect ((host,port)) Byteswritten=0 whilebyteswrittenlen (data):

(1)Select the most efficient table name order (only valid in the rule-based optimizer): The Oracle parser processes the table name from the FROM clause in a right-to-left order, and the last table written in the FROM clause (base table driving

Address: http://www.cnblogs.com/juddhu/archive/2012/03/07/2383101.htmlMeaning explanation:Decode (condition, value 1, return value 1, value 2, return value 2,... Value N, return value N, default value)The function has the following meanings:IF

We have to do not only write SQL, but also to write good performance of SQL statements.(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a

Join order in the 1.WHERE clause: Oracle parses the WHERE clause in a bottom-up order, according to which the connection between the tables must be written before the other where conditions, and the conditions that can filter out the maximum number

This article mainly introduces the commonly used escape functions, security functions in PHP, use these functions can filter most common attack means, such as SQL injection, the need for friends can refer to the 1. addslashes Addslashes escapes

(1) Simple integration, no associated database access:If you have a few simple database query statements, you can integrate them into a single query (even if there is no relationship between them). (2) Delete duplicate records: The most efficient

1. Create a test table and insert a piece of dataSql> CREATE TABLE test (id int);Table created.sql> INSERT INTO test values (1);1 row created.Sql> commit;Commit complete. 2. Create a function, used to delay, to this function will be circulated here

1.ORACLE Optimizer total 3 kinds A, rule (rule-based) B, cost (based on costs) C, CHOOSE (optional) Set the default optimizer to pass various declarations of optimizer_mode parameters in the Init.ora file, such as

First, use the Decode function for row-column:First of all, let's look at the most typical requirements: Student transcript report making "1" Table structure definition: CREATE TABLE SCORE ( ID Number (2), Student_name VARCHAR2 (10), SUBJECT

High-performance SQL statements will play a very important role in the operation of the software, the following small series of recently compiled SQL statements to optimize the data to share. First: Select the most efficient table name order (valid

MS SQL Server Query optimization methodThere are many reasons for the slow speed of queries, which are common1, no indexes, or no indexes (this is the most common problem with query slowness, is the flaw in programming)2, I/o throughput is small,

This article illustrates the method of Oracle to implement row and column conversion. Share to everyone for your reference, specific as follows: 1, the row and column conversion of fixed number Such as: Student subject Grade ---------------

(1) Select the most efficient table name order (valid only in the Rule-based optimizer): The Oracle parser processes the table names in the FROM clause in Right-to-left order, the last table (driving table), which is written in the FROM clause, is

Single-line function: For each row of data to be calculated after a row of output results,SQL single-line functions are divided into character functions, numeric functions, date functions, conversion functions, and other general functions based on

How do I write high-performance SQL statements?(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is

optimization Problems of databasefirst, the question of the proposedIn the early stage of application system development, due to less development database data, the query SQL statement, complex view of the writing of the performance of the SQL

See a very comprehensive SQL optimization article, in the development of the work often do not consider the performance of the lack of (at the beginning of the data volume is not seen the difference in speed). But the more you write, the more you

See a very comprehensive SQL optimization article, in the development of the work often do not consider the performance of the lack of (at the beginning of the data volume is not seen the difference in speed). But the more you write, the more you

(1)Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table (the underlying table,