"Go" database crud operations

Database CRUD Operations

Delete Table drop tables name

Second, modify the table

ALTER TABLE name adds column name data type (add indicates a column added)

ALTER TABLE name drop column name (column = Drop for drop means delete)

Third, delete the database

Drop database

Iv. crud Operations (create Add data read reading data update modify data delete remove data)

1. Add data (Create)

A:insert into + Nation values (' n002 ', ' hui ')--plus single quotes are converted to strings, English

B:insert into nation values (' n003 ', ') add only one column followed by empty to all additions that can be used

C:insert into Nation (code,) VALUES (' n004 ') add a column that can be used

D: Add insert into Nation (Code,name) values for multiple columns (' n004 ', ' Uighur ')

E: INSERT into table name dedicated to adding self-growth columns values (' p001 ', ' p006 ') self-growing column without tube, write second column directly

2. Deleting data (delete)

Delete from + table name--Delete all contents in table

Delete from + table name where ids=5 (delete this row)---where followed by a condition

3. Modify data (Uodate)

Update + table name set + column name = ' Set '---modify all the contents of this column

Update + table name set + column name = ' p006 ' where ids=6

Update + table name set + column name = ' p006 ', column name = ' p002 ' where ids=6-----separated by commas to modify multiple columns

Integer (int) is not required to add single quotes 0 (false) 1 (true)

4. Query data (10 kinds)

A1: Simple Query

SELECT * FROM table name--all data in the query table represents all columns

Select Code,name from table name--Query the specified column data

Select Code,name from table name--Check the data for the specified column

Select Code as ' Code ', name as ' from table ' name--Assign alias to column

A2: Conditional Query

SELECT * FROM table name where code= ' Check this line

SELECT * FROM table name where sex= ' true ' and nation= ' ' denotes side-by-side,--multi-conditional and relational

SELECT * FROM table name where sex= ' true ' or nation= '--multi-condition or relationship

A3: Range Query

SELECT * FROM table name where column name >40 and column name <50

SELECT * FROM table name where column name between 50--dedicated to range query

A4: Discrete Query

SELECT * FROM table name where column name in (', ' ', ')

SELECT * FROM table name where column name is not in (' ', ' ', ') inverse, not inside

A5: Fuzzy Query

SELECT * FROM table name where column name like '% BMW% '--check contains BMW's

SELECT * FROM table name where column name like ' BMW% '--look at the beginning of the BMW

SELECT * FROM table name where column name like '% BMW '--look at BMW end

SELECT * FROM table name where column name like ' BMW '-check equals BMW

SELECT * FROM table name where column name like '--e '--check the third one is E.

% represents any number of characters

-the underscore represents a character

A6: Sort Query

SELECT * FROM table name order BY column name--Default ascending sort

SELECT * FROM table name order by column name desc--descending order

SELECT * FROM table name order BY column name desc, column name asc--more than one conditional sort, preceded by a primary condition followed by a secondary condition

Desc Descending, ASC ascending, order by sort according to which column sort

A7: Paging Query

Select Top 5 * FROM table name--Query the first 5 data

Select Top 5 * from table name where code not in (select Top 5 code from car)

A8: Go to re-query (remove Duplicates)

Select DISTINCT column name from

A9: Group Query

Select brand from table name GROUP by Brand have Count (*) >2

Group BY having--indicates that count (*) >2--the number of each group based on a column grouping

A10: Aggregate function (statistical query)

Select COUNT (*) from table name--Query all data bars (per column)

Select COUNT (column name primary key) from table name--Query the number of all data bars in this column (execute fast)

Select SUM (column name) from table name--sum

Select AVG (column name) from table name--averaging

Select Max (column name) from table name--Seek maximum value

Select min (column name) from table name--Minimum value

"Go" database crud operations