1, Dynamic SQL
one of the powerful features of MyBatis is its dynamic SQL. If you have experience using JDBC or other similar frameworks, you can realize how painful it is to splice SQL statements according to different conditions. When splicing, make sure you don't forget the necessary spaces, and pay attention to omitting the comm ...
Posted on Mon, 06 Dec 2021 21:38:42 -0500 by DrDre
Using fluent mybatis, you don't have to write specific xml files. You can construct more complex business sql statements through java api to achieve the integration of code logic and sql logic. You no longer need to assemble queries or update operations in Dao, or reassemble parameters in xml and mapper. Compared with native Mybatis, Mybatis Pl ...
Posted on Sun, 05 Dec 2021 20:51:29 -0500 by scialom
Chapter 5 SQL predicate BETWEEN
scalar-expression BETWEEN lowval AND highval
Scalar expression - a scalar expression (most commonly a data column) that compares its value to the range of values between low and high values, including high values.lowval - an expression that resolves to a low collation sequence value ...
Posted on Sun, 05 Dec 2021 08:23:18 -0500 by yumico23
1. Procedural sql and embedded sql
1.1 embedded sql
Embedded SQL refers to including SQL statements into programming language. The embedded programming language, such as C / CPP / Java, is called the host language.
For embedded SQL, DBMS generally adopts the precompiled method, that is, the preprocessor of DBMS scans the source progra ...
Posted on Sun, 05 Dec 2021 05:57:36 -0500 by gerkintrigg
1, Functions of SQL language
SQL functionpredicateData definition (DDL)CREATE,DROP,ALTERData query (DQL)SELECTData manipulation (DML)INSERT,UPDATE,DELETEData control (DCL)GRANT,REVOKE,DENY
2, Data types supported by SQL
SQL data types are composed of 13 basic data types, including shaping, single precision, double precision, variable length c ...
Posted on Sun, 05 Dec 2021 03:00:44 -0500 by ineedhelp512
1. Specific contents
JDBC (Java DataBase Connectivity) is a java database connection. In other words, it uses the Java language to operate the database. It turns out that we operate the database by using SQL statements on the console, and JDBC sends SQL statements to the database in Java language. JDBC (Java Data Base Connecti ...
Posted on Sun, 05 Dec 2021 00:40:10 -0500 by empnorton
Tip: after the article is written, the directory can be generated automatically. Please refer to the help document on the right for how to generate it
This article is the author's study notes. It records in detail the author's understanding of SQL digital injection, and also introduces the complete process of using union joint q ...
Introduction to database transactions
1. Transaction: a group of logical operation units that transform data from one state to another.
2. Transaction processing (transaction operation): ensure that all transactions are executed as a work unit. Even if there is a fault, it cannot be modified
Change this way of execution ...
Posted on Thu, 02 Dec 2021 22:08:52 -0500 by jonsimmonds
1, Design table
Premise: the design table should first follow the three paradigms as needed
1NF – > column is the smallest atom that cannot be subdivided (avoid duplication);2NF – > primary key dependency (unique);3NF – > eliminate the transfer dependency (establish the primary foreign key Associati ...
Posted on Thu, 02 Dec 2021 19:58:22 -0500 by anoesis
This tutorial will show you how to quickly build streaming ETL for MySQL and Postgres based on Flink CDC.Flink-CDC project address:https://github.com/ververica/flink-cdc-connectorsThis tutorial's demo is based on a Docker environment and will be done in the Flink SQL CLI, involving only SQL, without a single line of Java/Scala code, or with an ...
Posted on Wed, 01 Dec 2021 23:09:41 -0500 by abhishek