如何使用sqlite选择满足特定条件的表格？ [英] How do I select table entires that meet specific conditions using sqlite?

问题描述

我为一个虚构的实验室社会创建了表格。其中一个表称为labbranch，我试图创建一个SQLite查询，选择等于或超过100米的表。



labbranch表有6行：labid，name，address，phone，sizeoflab，totaldeskspace。我只包括三个条目，其中两个超过100米。



谢谢



我尝试过：



SELECT sizeoflab

FROM lab

WHERE sizeoflab = 100 ;



当我尝试这个陈述时，我收到错误

解决方案

确定。我创建了你的表并填充它：

 创建 表 labbranch 
（
 labid  int ，
 name  varchar （ 50 ），
地址 varchar （ 50 ），
手机 varchar （ 50 ），
 sizeoflab  int ，
 totaldeskspace  int  
）; 
 
 插入 进入 labbranch 值（ 1 ，'  Lab1'，'  @ Lab1'，'  111'， 99 ， 99 ） ; 
 插入 进入 labbranch 值 （ 2 ，'  Lab2'，< span class =code-string>'  @ Lab2'，'  222'， 100 ， 100 ）; 
 插入 进入 labbranch 值 （ 3 ，'  Lab3'，< span class =code-string>'  @ Lab3'，'  333'， 101 ， 101 ）; 

请注意，该表有6个列（不是行）和3个行（条目）

您的要求是

Quote：

选择等于或超过100m的那些

所以我的预期结果基于您的描述是获取Lab2和Lab3的详细信息。



当我运行查询时你已经尝试过我收到一条错误信息：

Quote：

TypeError：无法获取属性'substring未定义或空引用这是因为你没有一个叫表实验室。通过使用正确的表名修复此问题：

  SELECT  sizeoflab 
  FROM  labbranch 
  WHERE  sizeoflab = 100; 

我跑了，我得到一个数字，100，返回。根据我的预期结果，我想要2行而不是1行，并且我目前的结果中没有任何有用的信息。



因此将其更改为

  SELECT  labid，name，sizeoflab  FROM  labbranch 
  WHERE  sizeoflab > =   100 ; 

给出结果：

  labid name sizeoflab  
 2 Lab2 100 
 3 Lab3 101 

I have created tables for a fictional lab society. One of the tables is called "labbranch" and I am trying to create an SQLite query that selects the ones that are equal to or over 100m.

The "labbranch" table has 6 rows: labid, name, address, phone, sizeoflab, totaldeskspace. I have only included three entries, two of which are over 100m.

thank you

What I have tried:

SELECT sizeoflab
FROM lab
WHERE sizeoflab=100;

When I tried this statement, I received an error

解决方案

Ok. I created your table and populated it thus:

create table labbranch
(
 labid int, 
 name varchar(50), 
 address varchar(50), 
 phone varchar(50), 
 sizeoflab int, 
 totaldeskspace int
);

insert into labbranch values(1,'Lab1','@Lab1','111', 99, 99);
insert into labbranch values(2,'Lab2','@Lab2','222', 100, 100);
insert into labbranch values(3,'Lab3','@Lab3','333', 101, 101);

Note that the table has 6 columns (not rows) and 3 rows (entries)
Your requirements are

Quote:

selects the ones that are equal to or over 100m

So my expected results based on your description are to get details for Lab2 and Lab3.

When I run the query you have already tried I get an error message:

Quote:

TypeError: Unable to get property 'substring' of undefined or null reference

This is because you do not have a table called lab. Fix that by using the correct table name:

SELECT sizeoflab
 FROM labbranch
 WHERE sizeoflab=100;

When I run that I get a single number, 100, returned. From my expected results I wanted 2 rows not one, and there isn't any useful information in the results I currently have either.

So change it to

SELECT labid, name, sizeoflab FROM labbranch
 WHERE sizeoflab >= 100;

Which gives the results:

labid name sizeoflab
2     Lab2 100
3     Lab3 101

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