bind variables

The instr function is a string function that returns the position of a string that appears for the first time in another string. Instr Function Format: instr ([start,] string1, string2 [, compare]) Nvl2 (A, B, C). If a is not null, B is

The instr function is a string function that returns the position of a string that appears for the first time in another string. Instr Function Format: instr ([start,] string1, string2 [, compare]) Nvl2 (A, B, C). If a is not null, B is returned.

Finding and running bad SQL in the system is an old topic. We need to analyze it based on our actual situation. You must not use the methods described below as a dogma. When these SQL statements are used, grouping operations are performed on the

Generally, each data block accessed by the database engine generates at least one logical read. Row prefetch is closely related to logical read. Row prefetch refers to when the client obtains data from the databaseYou can use a single row or

1. View tablespaces Select tablespace_name, file_name from dba_data_files; 2. Create a statspack tablespace Create tablespace perfstat datafile 'd:/Oracle/oradata/perfstat. dbf' size 500 m The tablespace should be as big as possible. 3. Install

Index full scan and index fast full scan look similar to each other. They are both common and personalized. The commonality between the two is that scanning is not required.You can directly return all the required data through the index. This is

Case statements and case expressions are an important part of PLSQL Process Control. Although they are easy to use, they are easy to confuse. This article describes the case statement and the case expression, and provides an example This helps you

Function and closure 1 member Method Java functions exist. The way to append a function to a class is to append a method to it.  2 Local Method The local method exists in a method. If one method in a class is private and only one method is used,

Multiple unrelated columns are combined to form a PL/SQL record type, which can be processed as a whole. In addition, PL/SQL record types can be performedNesting and defining Union arrays and nested tables based on PL/SQL records. This article first

Boolean is a type of PL/SQL data. Logical values are true and false. Only logical operators can be applied to boolean variables. The Database SQL type does not support BooleanType. Only PL/SQL is supported. Therefore, you cannot insert or retrieve

The results returned by the recent SQL query cause a ORA-06502 error to the PL/SQL variable. The error description is ORA-06502: PL/SQL: numeric or value error: character string buffer too small. obviously, the length of the character variable

Database performance is an eternal topic, that is, how to use less resources to achieve more efficient performance. The Oracle system parameter resource_limit is a parameter used to control the user's usage of database resources. It is enabled when

The Oracle monitoring index feature allows us to roughly determine whether an index is used. This is because the index is monitored when statistics are collected in Oracle 10 Gb, which is not produced by SQL statements. In the case of 11g, there is

Some netizens recently mentioned why the historical execution plan of SQL statements cannot be viewed in dba_hist_ SQL _plan. This problem is due to the fact that the threshold value set by Oracle does not capture all SQL statements by default,

Oracle db_file_multiblock_read_count is an important global parameter in Oracle, which can affect the system level and sessioin level. It is mainly used to minimize the number of data blocks that Oracle can read at a time in order during table scan.

For Dev and UAT environments, databases must be in archive mode, but do not need to be backed up. Therefore, the constant increase in archive archiving logs results in a large amount of disk space consumption. In this case, you can use a shell

Generally, when you submit an SQL statement, there will always be one or more waiting events. That is to say, the process has to wait because the required resources are occupied. Oracle provides us with an available view of these wait events. Based

From: http://www.iteye.com/topic/508161 Recently, javaeye found that many comrades know little about SQL optimization. Recently, I have summarized several articles for reference only. However, a few of them may depend on the situation, most of

From the design of the Oracle shared pool and the PL/SQL writing method recommended by Oracle, we can see that variable binding has a great impact on performance, how to bind variables in PL/SQL? First, let's take a look at the usage of not using

Oracle technical Q & Today, I talked to a senior Oracle expert about a lot of technical problems. He also came up with a few questions and asked me at random, I found that there are still a lot of dry goods in the seemingly simple questions. Many