Tauākī Tīpako SQL

Ko te SELECT tauākī i roto i te SQL whakamahia ki te tiki raraunga mai i te teepu pātengi raraunga.

Ka taea e taatau te whakamahi i te SELECT tauākī ki te tiki raraunga mai i te (pou) kua tohua, o nga pou katoa ranei.



SQL SELECT Syntax

Ko te SELECT he kupu whai ake tenei ko te tauākī:


SELECT column1, column2, ... FROM table_name;

SQL SELECT Tauira Tauira Tauira

Whakaarohia he teepu taatau ko 'Nga Kaimahi' me nga korero e whai ake nei:

+------------+-----------+----------+------------+ | EmployeeID | FirstName | LastName | Department | +------------+-----------+----------+------------+ | 1

| Mark
| Otto
| Finance | | 2

| Jacob
| Thornton | IT
| | 3

| Su
| Bird
| Marketing | | 4

| Sam
| Burger | IT
| +------------+-----------+----------+------------+


Tīpakohia Mai i te Tīwae

Hei kowhiri i te pou “Tari” mai i te teepu “Kaimahi”:


SELECT Department FROM Employees;

Putanga:

+------------+ | Department | +------------+ | Finance | | IT
| | Marketing | | IT
| +------------+


Tīpakohia Mai i te Tīwae Maha

Hei kowhiri i nga pou “Tari” me te “Kaimahi” mai i te teepu “Kaimahi”:

SELECT EmployeeID, Department FROM Employees;

Putanga:

+------------+------------+ | EmployeeID | Department | +------------+------------+ | 1

| Finance | | 2

| IT
| | 3

| Marketing | | 4

| IT
| +------------+------------+


SELECT * Tauākī

Hei kowhiri i nga pou katoa mai i te teepu “Kaimahi”:


SELECT * FROM Employees;

Putanga:

+------------+-----------+----------+------------+ | EmployeeID | FirstName | LastName | Department | +------------+-----------+----------+------------+ | 1

| Mark
| Otto
| Finance | | 2

| Jacob
| Thornton | IT
| | 3

| Su
| Bird
| Marketing | | 4

| Sam
| Burger | IT
| +------------+-----------+----------+------------+


Nga Hua Taatari Ma Te Whiwhi WHERE

Ka taea e taatau te taatai ​​i nga hua mai i te SELECT uiui ma te whakamahi i te WHERE rara.

Hei tauira, ki te kowhiri i nga kaimahi katoa kei te whakamahi i te 'Tari IT':

SELECT * FROM Employees WHERE Department='IT'

Putanga:


+------------+-----------+----------+------------+ | EmployeeID | FirstName | LastName | Department | +------------+-----------+----------+------------+ | 2

| Jacob
| Thornton | IT
| | 4

| Sam
| Burger | IT
| +------------+-----------+----------+------------+

Waihoki, ki te kowhiri i nga Ids kaimahi katoa kei roto i te 'Tari IT' e whakamahia ana e maatau:

SELECT EmployeeID FROM Employees WHERE Department='IT'

Putanga:

+------------+ | EmployeeID | +------------+ | 2

| | 4

| +------------+