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1.DMSQL classification DML (data management language) - insert - update - delete - select DDL (data definition language) - create - drop - alert - truncate DCL (data control language) - grant - revoke TCL (transaction control) - commit - rollback - savepoint 2. Writing specification of SQL statement Keywords cannot be abbrev ...

WEB vulnerability - query method and error reporting blind note preface During SQL injection, many injections will not be echoed. The reason for not echoing may be the problem of the query method of SQL statements (the returned results of insert, update and delete only prompt completion / incomplete). At this time, we need to use relevant err ...

1, Preparation before installation 1.1 create RAID5 disk array To view the number of hard disk devices, use the ll / dev/sd * command [root@TradeProbe ~]# ll /dev/sd* brw-rw----. 1 root disk 8, 0 8 May 15:36 /dev/sda brw-rw----. 1 root disk 8, 1 8 May 15:36 /dev/sda1 brw-rw----. 1 root disk 8, 2 8 May 15:36 /dev/sda2 brw-rw----. 1 root di ...

1. Use Navicat Premium to connect oracle and mysql To connect to local oracle, you need to download the corresponding oci file OCI download address Extract the downloaded oci file, Navicat premium - > tools - > Options, and find the extraction address of oci configuration oci file 2. Problems encountered in migration and Solutions 1. T ...

Redis Server Startup Process Today, let's start with Redis server. We know that the main function is the entry to Redis's entire running program, and that when a Redis instance is running, it also starts executing from this main function. Also, since Redis is a typical Client-Server architecture, once the Redis instance starts running, the Re ...

1, SQL overview SQL (structured Query Language) is a structured Query Language used to access, query, update data and manage relational database systems 1.1 SQL development SQL was introduced by IBM in 1981. Once it was applied in the database, it became the general specification of the database The specification of SQL is determined b ...

Hello, I'm Lao Wu. You can also call me classmate Wu. Younger friends can also call me senior brother Wu. Welcome to the world of data analysis with me and learn together! Interested friends can pay attention to me Data analysis column , there are many high-quality articles to share with you. In addition, you are also welcome to pay attention ...

Meaning: it is also called multi table query. When the query fields come from multiple tables, the join query will be used Cartesian boarding phenomenon: Table 1 has n rows, table 2 has m rows, and the result = n*m rows Cause: there is no valid connection condition How to avoid: adding valid connection conditions Classification: 1. Classifi ...

prefaceRecently, a classmate asked how to compile and install PostgreSQL under Ubuntu. This time, let's talk about how to install PostgreSQL database in Ubuntu operating system. So, installing PostgreSQL is the easiest thing for DBA s. We know that PostgreSQL has three installation methods in RedHat family system, namely source code installatio ...

Insert multiple messages at a time SQL34 link address: https://www.nowcoder.com/practice/51c12cea6a97468da149c04b7ecf362e?tpId=82&&tqId=29802&rp=1&ru=/ta/sql&qru=/ta/sql/question-ranking Title Description: The topic has already executed the following statement: drop table if exists actor; CREATE TABLE actor ( actor_id ...