财政年度表之建表约束-Mysql Tutorial-php.cn

Home

Database

Mysql Tutorial

财政年度表之建表约束

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 07, 2016 pm 02:55 PM

createconstraint

财政年度表约束无 Create Table FinancialYear(fiscal_year INTEGER NOT NULL PRIMARY KEY,start_date DATE NOT NULL,CHECK ((EXTRACT(YEAR FROM start_date)=fiscal_year-1)AND (EXTRACT (MONTH FROM start_date)=10)AND (EXTRACT(DAY FROM start_date)=1),

财政年度表约束

Create Table FinancialYear
(fiscal_year INTEGER NOT NULL PRIMARY KEY,
start_date DATE NOT NULL,
CHECK ((EXTRACT(YEAR FROM start_date)=fiscal_year-1)
AND (EXTRACT (MONTH FROM start_date)=10)
AND (EXTRACT(DAY FROM start_date)=1),
end_date DATE NOT NULL,
CONSTRAINT valid_end_date
CHECK ((EXTRACT (YEAR FROM end_date)=fiscal_year)
AND (EXTRACT (MONTH FROM end_date)=9)
AND (EXTRACT (DAY FROM end_date)=30)))

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

When should you use a composite index versus multiple single-column indexes?Apr 11, 2025 am 12:06 AM

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

How to identify and optimize slow queries in MySQL? (slow query log, performance_schema)Apr 10, 2025 am 09:36 AM

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL: Essential Skills for DevelopersApr 10, 2025 am 09:30 AM

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.

Describe MySQL asynchronous master-slave replication process.Apr 10, 2025 am 09:30 AM

MySQL asynchronous master-slave replication enables data synchronization through binlog, improving read performance and high availability. 1) The master server record changes to binlog; 2) The slave server reads binlog through I/O threads; 3) The server SQL thread applies binlog to synchronize data.

MySQL: Simple Concepts for Easy LearningApr 10, 2025 am 09:29 AM

MySQL is an open source relational database management system. 1) Create database and tables: Use the CREATEDATABASE and CREATETABLE commands. 2) Basic operations: INSERT, UPDATE, DELETE and SELECT. 3) Advanced operations: JOIN, subquery and transaction processing. 4) Debugging skills: Check syntax, data type and permissions. 5) Optimization suggestions: Use indexes, avoid SELECT* and use transactions.

MySQL: A User-Friendly Introduction to DatabasesApr 10, 2025 am 09:27 AM

The installation and basic operations of MySQL include: 1. Download and install MySQL, set the root user password; 2. Use SQL commands to create databases and tables, such as CREATEDATABASE and CREATETABLE; 3. Execute CRUD operations, use INSERT, SELECT, UPDATE, DELETE commands; 4. Create indexes and stored procedures to optimize performance and implement complex logic. With these steps, you can build and manage MySQL databases from scratch.

How does the InnoDB Buffer Pool work and why is it crucial for performance?Apr 09, 2025 am 12:12 AM

InnoDBBufferPool improves the performance of MySQL databases by loading data and index pages into memory. 1) The data page is loaded into the BufferPool to reduce disk I/O. 2) Dirty pages are marked and refreshed to disk regularly. 3) LRU algorithm management data page elimination. 4) The read-out mechanism loads the possible data pages in advance.

MySQL: The Ease of Data Management for BeginnersApr 09, 2025 am 12:07 AM

MySQL is suitable for beginners because it is simple to install, powerful and easy to manage data. 1. Simple installation and configuration, suitable for a variety of operating systems. 2. Support basic operations such as creating databases and tables, inserting, querying, updating and deleting data. 3. Provide advanced functions such as JOIN operations and subqueries. 4. Performance can be improved through indexing, query optimization and table partitioning. 5. Support backup, recovery and security measures to ensure data security and consistency.

See all articles