Programmer Group

The development of students in recent days reflects a problem, there is a Java night program, used to delete historical expired data regularly every day, before March 10, after internal testing, but these two days again, there is a SQL statement has been reported ORA-01752 error, due to a recent development library migration, from one computer ...

Lucene 3.0 Optimized Operation What is Lucene? We use Lucene, mainly to do in-site search, that is, to search for resources within a system. For example, BBS, BLOG articles search, online store goods search, etc. So, after learning Lucene, we can add full-text search function for our own project. The exercises related to this learning con ...

This article describes how to start MongoDB and connect with a shell. Here are some of the operations we are familiar with in mysql 1. Create a database MongoDB The grammatical format for creating the database is as follows: ``` use DATABASE_NAME ``` //If the database does not exist, create the database, otherwise switch to the specified d ...

MyBatis is a lightweight ORM library. MyBatis can store POJO classes into databases or convert data from databases into POJO classes. Unlike Hibernate and other libraries, MyBatis recommends using the way of writing SQL statements in XML configuration to convert data, which greatly improves flexibility. Here is a simple example to illustrate t ...

01 Project Training Objectives * A: Project training objectives * a: Project objectives * Comprehensive use of the knowledge points learned before * Skilled in method invocation operation among View layer, Service layer and Dao layer. * Skilled dbutils operation database tables to complete add, delete and change chec ...

Data constraints 1. Data constraints: Adding some data constraints to the table can achieve the effect of constraining users to manipulate data. 2. default constraints When no value is added to the field, a default value is given. If the value added to the field constrained by the default value is null, its field value is null. Cre ...

New Statement Handler Analysis of Configuration SimpleExecutor's doUpdate method has been analyzed above: 1 public int doUpdate(MappedStatement ms, Object parameter) throws SQLException { 2 Statement stmt = null; 3 try { 4 Configuration configuration = ms.getConfiguration(); 5 StatementHandler handler = configuration.n ...

Cumulative Measures refer to aggregating data from the first element in the sequence to the current element, such as statistics of cumulative sales from January to the current month of each year. This article explains how to realize the cumulative monthly sales volume and amount in the sales order example, and makes corresponding modifications ...

PHP (hypertext preprocessor) can be used to build small websites. When users need to register and login, they need to match the background database to register and login. There are many traditional ways and steps. They need to connect the database first and insert sql statements. <?php header("Content-type: text/html; charset=utf-8"); $conn ...

PreparedStatement is a sub-interface of Statement, and its name shows that it is a "ready" Statement, so it represents a pre-compiled SQL statement; the object to obtain it can be obtained by the preparedStatement (String sql) method in Connection, where the parameters are SQL statements with placeholders, so it is in it. Some setXxx( ...