MySQL basics [naming convention]

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First, the naming problem of MySQL under different systems

1.Linux

1. Database name and table name are strictly case-sensitive;
2. Table aliases are strictly case-sensitive;
3. Column names and column aliases are case-insensitive in all cases;
4. Variable names are also strictly case-sensitive;

2. Windows

• All are case insensitive

Second, a unified writing standard is recommended

• The database name, table name, table alias, field name, field alias, etc. are all lowercase. When defining databases, tables, and columns, all use lowercase letters and underscores, and do not use any capital letters.

• SQL keywords, function names, bind variables, etc. are capitalized

Third, naming rules

• Database and table names cannot exceed 30 characters, and variable names are limited to 29
• Must only contain A–Z, a–z, 0–9, _total63 characters
• Database name, table name, field name and other object names do not contain spaces
• In the same MySQL software, databases cannot have the same name; in the same database, tables cannot have the same name; in the same table, fields cannot have the same name
• You must ensure that your fields do not conflict with reserved words, database systems, or common methods.If you insist, use ` (emphasis) in SQL statements
• Keep field names and types consistent, be sure to consistent when naming fields and assigning data types to them.If the data type is integer in one table, don't change it to character in another table

Example:

#The following two sentences are the same, not case sensitiveshow databases;SHOW DATABASES;#create form#create table student info(...); #The table name is wrong because there are spaces in the table namecreate table student_info(...);#Where order uses ``floating number, because order and predefined identifiers such as system keywords or system function names have the same nameCREATE TABLE `order`();#When making an alias, as can be omittedselect id as "ID", `name` as "name" from t_stu;#If there is no space in the field alias, you can omit ""select id as id, `name` asNamefrom t_stu;#Error, if there are spaces in the field alias, you cannot omit ""select id as id, `name` asNamefrom t_stu;