Programmer Think

Environmental Information red hat linux64  gi 11.2.0.4  oracle 11.2.0.4 Problem Phenomena After installing gi software and oralce database software, the database is built through the dbca user interface. It is found that the database can be built normally on node1, not on node2. The dbca library building process errors on node2. Figur ...

[select] SQL statement query join(left/right) two-table join/multi-table join //Multi-table Joint Survey: $sql = 'SELECT * FROM news LEFT JOIN (news_type, news_photo)ON (news_photo.n_id=news.n_id AND n_type=news_type.id)'; //Joint investigation of two tables: $sql = 'SELECT * FROM s LEFT JOIN sc ON s.sno=sc.sno'; Three Tables Joint Ch ...

1, Background Durid is a widely used database connection pool, which has superior performance, powerful monitoring mechanism, and also supports expansion through the mechanism of filter. Druid has a StatFilter for slow sql recording, but I found some shortcomings in using it: The print log of this Fi ...

1 multi meter 1.1 multi table description In actual development, a project usually needs many tables to complete For example, the database of a shopping mall project needs many tables: user table, classification table, commodity table, order table 1.2 disadvantages of single table 1.2.1 table building C ...

Initialize global configuration through settings configuration When it comes to initializing the global Configuration of Mybatis through settings, it is difficult for us to bypass the Configuration object of Mybatis. Configuration object is undoubtedly one of the core objects of Mybatis. It defines many properties and methods. In the process of ...

Before  , there was a small test project that needed to synchronize some local data to Alibaba cloud database regularly. It was implemented by executing LOAD DATA with the most mechanical script. Here is a brief introduction. LOAD DATA can quickly read text file data into the table (LOAD DATA is us ...

Catalogue 1. Textbook [P281-P287] 2. SQL statement [create data table (6 tables), insert data] 2.1. Chinese field representation 2.2. English field representation 3. New view 3.1, 6 table general view 3.2. Total credits (student number, credits) 3.3. Total credit statement 4. Query exercise 1. Textbook [P281-P287] ...

SQL parsing order Next, let's take a look at the past and present life of an SQL statement. First, let's look at the sample statement: SELECT DISTINCT < select_list > FROM < left_table > < join_type > JOIN < right_table > ON < join_condition > WHERE < wh ...

Before moving on to dynamic sql, let's start by saying that a user's id in real development is usually out of order, such as random generation using UUID s. Write one below. public class UUIDGenerate { public static String getIdByUUID(){ return UUID.randomUUID().toString().replaceAll("-" ...

Content Summary constraint condition Relationships between tables (constraints) Modify the full syntax of the table Copy Table constraint condition Default default """ # Supplement: You can specify fields when inserting data create table t1 ( id int, name varchar(16) ); insert into t1 (name, id) values ('samuel', 1); create table ...