ios-Single-table operations common SQL

--Create a data table that defines the structure of the stored Data information table--CREATE TABLE t_student (Name text, age integer, Phoneno text);--Deleting a data table is usually used when you don't need to use a table , which is rarely used in daily development--DROP TABLE t_student;--new data content, in SQL statements, strings need to be enclosed in single quotation marks--syntax format for INSERT statement:--INSERT into table name (Field 1, Field 2, ...) VALUES (Field 1 value, field 2 value, ...)--INSERT into T_person (name, age, gender, height) VALUES (' Floret 1 ', 1, 1.62);--Update Database Content--Update all records--UPDATE t_person SET name = ' King two leper ';--conditional modification where (where to modify, where to manipulate the record)--UPDATE t_person SET name = ' Small Fang ' WHERE gender = 1;--use and to set the conditions--use or to set or condition--Update the syntax format of a record--UPDATE table name SET Field 1 = Field 1 value, field 2 = Field 2 value, ... WHERE to modify the condition--UPDATE t_person SET name = ' Simon blows Snow ', age = a WHERE age = $ and height = 1.65;--UPDATE t_person SET name = ' Goku ' WHERE age = OR height = 1.72;--Deleting Records--syntax formatting to delete--Delete from table name WHERE to delete condition--DELETE from T_person WHERE height = 1.8;--Query Instructions--SELECT * from T_person;--Conditional Query--check all the men.--SELECT * from T_person WHERE gender = 1;--Inquiry age greater than 10 years old, is also a man--SELECT * from T_person WHERE age > and gender = 0;--Query the total number of records in the person table---SELECT Count (*) from T_person;--Query the tallest height--SELECT max (height) from T_person;--SELECT min (age) from T_person;--Check the average height of all men---SELECT avg (height) from T_person WHERE gender = 0;--Paging Query--starting from the No. 0 record, query 3 records--the first parameter of the LIMIT indicates: Start the query from the number of rows, the starting line is 0--The second parameter of LIMIT indicates the number of records that the query needs to query--SELECT * from T_person LIMIT 0, 3;--SELECT * from T_person LIMIT 3, 3;--SELECT * from T_person LIMIT 6, 3;--Sort--Order By field name to sort--ASC indicates ascending--desc = Descending--if more than one field participates in the sort, first field is followed, and so on, that is: the first field has the highest sort priority! SELECTHeight, name, gender, age fromT_personORDER  byAgeASC, heightDESC;