How to write sql is not equal to

1. There are two ways to express inequality in SQL, one is "" (without quotation marks), the other is "!=" (without quotation marks), the usage is the same.

2. That is where a 100; or where a != 100;

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Structured Query Language (Structured Query Language), referred to as SQL, is a special-purpose programming language, a database query and programming Language for accessing data and querying, updating, and managing relational database systems.

Structured Query Language is a high-level non-procedural programming language that allows users to work on high-level data structures. It does not require users to specify the data storage method, nor does it require users to understand the specific data storage method, so different database systems with completely different underlying structures can use the same structured query language as the interface for data input and management. Structured Query Language statements can be nested, which makes it extremely flexible and powerful.

The SQL language was proposed by Boyce and Chamberlin in 1974 and was first implemented on SystemR, a relational database system developed by IBM. Because of its outstanding advantages such as rich functions, convenient and flexible use, simple and easy to learn language, it is very popular among the computer industry and computer users. In October 1980, SQL was approved by the Database Committee X3H2 of the American National Standards Institute (ANSI) as the American standard for relational database languages. Standard SQL was announced in the same year. Shortly thereafter, the International Organization for Standardization (ISO) also made the same decision. .

SQL can be functionally divided into three parts: data definition, data manipulation and data control.

　The core part of SQL is equivalent to relational algebra, but it has many features that relational algebra does not have, such as aggregation, database updates, etc. It is a comprehensive, versatile, and extremely powerful relational database language. Its characteristics are:

　1. Integration of data description, manipulation, control and other functions.

　2. Two ways of use, unified grammatical structure. SQL can be used in two ways. One is online interactive use. SQL in this way is actually used as a self-contained language. Another way is to embed it into some high-level programming language (such as C language, etc.) for use. The former method is suitable for non-computer professionals, and the latter method is suitable for professional computer personnel. Although they are used in different ways, the grammatical structure of the languages ​​used is basically the same.

　3. Highly non-procedural. SQL is a fourth-generation language (4GL). Users only need to ask "what to do" and do not need to specify "how to do it". Access path selection and specific processing operations are automatically completed by the system.

　　4. The language is concise, easy to learn and use. Although SQL has powerful functions, the language is very concise, and only 9 verbs are used for the core functions. The syntax of SQL is close to spoken English, so it is easy for users to learn and use.

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