Keyword is case insensitive
For example, select, from, case can be
Identifiers are case-sensitive
For example, table name, column name
If the identifier is not double-quoted, the default is uppercase
Identifiers are executed in the original case if double quotation marks are added
However, when the table name is enclosed in double quotation marks,
Originally the default is the uppercase table name, plus double quotation marks in accordance with the original lowercase query, query not;
Now we're going to capitalize on it,
Then can be queried to;
Just remember, no double quotes, automatically converted to uppercase, but with double quotation marks, it is case-sensitive, when we create table names, column names are not added double quotation marks, it is automatically determined by the capitalization rules;
Writing specifications for SQL statements
All table names, column names all lowercase
keyword, built-in function name all uppercase
Unselected rows indicate no data in the table;
SQL statement case-sensitive issues