decode function

1. decode function usage The DECODE function is one of the powerful functions of oracle pl/SQL. Currently, only oracle SQL provides this function, and other database vendors do not yet implement this function. What is the purpose of DECODE? First,

The DECODE function is one of the powerful functions of Oracle PL/SQL. Currently, only oracle SQL provides this function, and other database vendors do not yet implement this function. What is the purpose of DECODE? First, let's construct an example.

Overview The voip function of Android is available in the directory frameworks/base/voip. It includes a package that supports rtp. RTP support The RTP support package is located in the directory frameworks/base/voip/java/android/net/rtp. It mainly

function Introduction　　The Decode function is one of the most powerful functions of Oracle PL/SQL and is currently available only to Oracle Corporation, where SQL implementations of other database vendors do not yet have this function.What is the

The following article reproduced from: http://www.cnblogs.com/200911/archive/2012/07/26/2610018.html, thank youThis feature greatly improves the performance of SQL execution and saves memory usage: we find that the statistics of single-table data

The Oracle tutorial you are looking at is: Oracle SQL Performance Tuning Series learning three. 8. Use the Decode function to reduce processing time Use the Decode function to avoid repeatedly scanning the same record or repeating the same

oracle| Performance | optimization 8. Use the Decode function to reduce processing time Use the Decode function to avoid repeatedly scanning the same record or repeating the same table. For example: SELECT COUNT (*), SUM (SAL) From

1. Avoid using "*" in the SELECT clauseWhen you want to list all columns in the SELECT clause, it is a convenient way to refer to ' * ' Using a dynamic SQL column. Unfortunately, this is a very inefficient approach. In fact, during the parsing

Although each database is supported by SQL statements, each database has its own operation function supported by each database, which is a single-line function, and if you want to do database development, except to use SQL, is to learn more

Oracle note (5) single-row functions although each database supports SQL statements, each database also has the operation functions supported by each database. These are single-row functions, if you want to develop a database, you need to learn more

Example of implementing JSON deserialization Class Object in Python, json serialization Our network protocol is generally to convert data into JSON before transmission. Previously, serialization and deserialization were implemented in Java, both

Common Oracle SQL skills (conversion) and oraclesql skills 1. Avoid "*" in the SELECT clause.When you want to list all columns in the SELECT clause, using dynamic SQL COLUMN reference '*' is a convenient method. unfortunately, this is a very

A, avoid using the IS null and is not NULL operation on an indexed columnTo avoid using columns that can then be empty in the index, Oracle will not be able to use that index. For a single-column index, if a null value is included, the index does

Decode is translated as decoding or decoding, because it can translate the query results into content that is easy for the user to understand.Grammar:Expr: An expressionSearch: Searching for valuesResult: Results valueDefault: DefaultsThe first

The ORACLE tutorial is: Oracle SQL Performance Optimization Series III. 8. Use the DECODE function to reduce processing timeYou can use the DECODE function to avoid repeated scan of the same record or join the same table.For example:Select count (*),

Oracle SQL Performance 1. ORACLE optimizer:. RULE (based on Rules) B. COST (COST-based) c. CHOOSE (optional) sets the default optimizer. various declarations of the OPTIMIZER_MODE parameter in the ora file, such as RULE, COST, CHOOSE, ALL_ROWS,

Use case and decode of Oracle functions and compare their performance to achieve logical judgment. Oracle's DECODE function is very powerful. If you use it flexibly, you can avoid multiple scans. Use case and decode of Oracle functions and compare

SQL statement DECODE () and NVL () function usage SELECT DECODE (WP01.ONDO _ KBN, 0 ,'?? For example, when '1, 'normal temperature ', 2, and 'cold recovery') AS ONDO_KBNFROM WP01_S_HAITOTAL WP01 // analysis: When WP01.ONDO _ KBN = 0 "?? When

SQL Server performance optimization skills, SQL Server Performance Optimization 1. Select the most efficient table name sequence (only valid in the rule-based Optimizer) The SQL Server parser processes the table names in the FROM clause in the order

From: http://hi.baidu.com/freeperson/blog/item/2f9eafd48a693909a08bb70f.html   Here we provide optimization of the execution performance, rather than the background database optimizer: According to various issues in database development