in relational database each should unique

Tags: Mongo lan mon min idt dex font Use admin  One: Normal index 1 to create a new database > Use Toto; Switched to DB Toto > Show DBS; Admin (empty) Local 0.078GB > Use Toto; Switched to DB Toto > DB Toto > 2 Create - million-piece data > for (var i=1; I ... db.c3.insert ({name: "Zhangsan", age:i}); ... } >db.c3.count (); 3 No index lookup >db.c3.find ({age:500000}). Explain (); 4 bit Age field to create an index Db.c3.

Tags: empty god name for Sys + + ... lang csdn?? One: Normal index 1 to create a new database > Use Toto; Switched to DB Toto > Show DBS; Admin (empty) Local 0.078GB > Use Toto; Switched to DB Toto > DB Toto > 2 Create - million-piece data > for (var i=1; I ... db.c3.insert ({name: "Zhangsan", age:i}); ... } >db.c3.count (); 3 No index lookup >db.c3.find ({age:500000}). Explain (); 4 bit Age field to create an index Db.c3.en

Relational Database V. S. Non-relational database, relational database v. sThe most important feature of a relational database is transactio

Label:1. Relational database Relational database refers to a database that uses a relational model to organize data. The relational model was first proposed by IBM researcher Dr. E.f.co

Label: Database Paradigm when designing the relational database, we should design a reasonable relational database to conform to different specifications, and the different norm requirements are called different paradigms, and the higher paradigm

1. Relational databaseRelational database refers to a database that uses a relational model to organize data.The relational model was first proposed by IBM researcher Dr. E.f.codd in 1970, and in the following decades, the concept of rel