Union two tables with different number of columns

I have two tables (Table A and Table B). The two tables have different number of columns - let's say table A has more columns. How can I merge these two tables and get null values ​​on columns that table B doesn't have?

P粉879517403 2023-08-24 18:54:05 0  2  561

mysql - Some problems with label tables

I just learned mysql and am not familiar with mysql. Now I have three tables like this: article table id title content 0 hello world 1 hey .... question table id title content 0 hello world 1 hey .... label table id name avatar 1 java .... 2 js .... two...

世界只因有你 2017-05-18 10:49:42 0  2  743

Vue - virtual scrolling of tables

I would like you to recommend me a package that can utilize virtual scrolling/recycler scrolling of tables in Vue. I tried these two libraries: https://github.com/tangbc/vue-virtual-scroll-list https://github.com/Akryum/vue-virtual-scroller I am able to generate a virtual scrolling list of items, bu...

P粉401901266 2023-12-10 15:53:07 0  1  688

java - database query multiple tables

Prerequisite oralce, mybatis now has multiple tables. I now need to count the amount of information in each table, that is, count(*). My current method is to write multiple methods, such as in mapper: long selectCountA; long selectCountB; long selectCountC ; In this case, I want to...

習慣沉默 2017-05-18 10:45:06 0  4  804

Delete from multiple tables in one statement

Using MySQL, I'm trying to delete multiple records from multiple tables at once. Initially I thought I could do this: DELETEt1,t2FROMtable1t1JOINtable2t2ONt1.id=t2.table1_idJOINtable3t3ONt1.id=t3.table1_idWHEREt1.idIN(?,?,?,?); However, if there are no existing records in table2, I should change the...

P粉716228245 2023-08-18 10:28:49 0  1  540

Questions about foreign keys to tables

The teacher would like to ask, why not create foreign key links directly in MySQL? It is the relationship between the foreign key that directly links the two tables.

clean 2020-04-15 00:05:35 0  1  1038

Delete from two tables in one query

I have two tables in MySQL #messagestable:messageidmessagetitle..#usersmessagestableusersmessageidmessageiduserid.. Now if I want to delete from message table it is ok. But when I delete the message by messageid, the record still exists on usersmessage and I have to delete from both tables immediate...

P粉401901266 2023-08-27 13:45:48 0  2  503

mysql - Problem with database splitting into tables and databases?

As a simple example, take the order form. For example: 1 merchant. The uids of the 10 users are [1,2...,10]. 10 orders from 10 users are in one data table A. Now we need to divide the tables horizontally according to the uid, and divide the 10 orders into 10 tables, that is, there are 10 tables A0, ...

为情所困 2017-05-18 10:49:13 0  1  588

MySQL query to convert rows of multiple tables into columns

I need to ask you about MySQL select query from 3 tables. I have 3 similar tables: table_1menu_id|menu_name1|menu12|menu2table_2item_id|menu_id|item_name1|1|item12|1|item23|2|item34|2|item4table_3price_id|item_id|currency_code|price1|1| EUR|3.652|1|USD|3

P粉882357979 2023-08-13 16:02:22 0  1  564

How to delete an entire row of data in multiple tables with a certain ID in MySQL?

For example, I have four tables now. The columns of each table are different, but they all have an ID column. In some tables, the ID is not used as the primary key. I now need to sort the row with the ID value 12 in the four tables based on the ID value. All the data is deleted, how to write a DELET...

巴扎黑 2017-06-22 11:54:42 0  3  927

Application of subtracting numerical values ​​in different tables

I have two tables: table AIDNumberProfile1100Baker275Fields3100Wayward table BIDNumberTagSender150onchris250offjames I am trying to subtract the value table CIDNumber150225 with the same ID number from table A and table B

P粉854119263 2023-08-28 19:28:28 0  1  388

How to determine whether the database libraries and tables exist?

For example, how to determine whether the database libraries and tables exist?

正念的奇迹 2017-08-08 10:47:41 0  2  1248

How to use cursors to extract data from multiple tables

I have a query that returns multiple tables, something like this: SELECTTableName,DatabaseName+'.'+TableName,ColumnNameFROMDBC.ColumnsWHEREColumnName='id' I need to loop through these tables by looking at the information stored in them in order to get only specific table. I tried the code below, usi...

P粉141035089 2023-08-16 13:12:27 0  2  586

When getting data from multiple tables, how to query based on entries in the table in SQL grouping

I have two tables click 2.ride click table id | time ride table id | timestamp I want to get data from both tables GROUPBYEXTRACT(DAYFROMride.timestamp) but only if I have same day in both tables I only get the data when an entry is made, but I need the data regardless of whether the two tables have...

P粉038856725 2024-04-04 08:58:17 0  1  450

Will changing the MYSQL table engine from MYISAM to INNODB cause data corruption?

I have a simple question. I have a mysql database. I have 2 tables using MYISAM that I want to change to INNODB, one of the tables has 1.000 rows, is there a risk of my data/rows getting corrupted if I do this change?

P粉412533525 2023-09-06 18:42:42 0  1  413

Creating tables is tip #1286 - Unknown storage engine 'InnoDB'

Creating tables is tip #1286 - Unknown storage engine 'InnoDB'

元曦 2017-08-21 14:13:04 0  2  1513

Information from multiple tables in a foreach loop. laravelle 8

I think try creating a table that is passed through a foreach loop that has to pick related data from two separate tables. Actual situation, making a loan management web application, I have to show the lender the bid data he made to the borrower, but in order to make the display table complete, it n...

P粉025632437 2024-03-19 17:02:42 0  1  446

Query data from multiple tables using SQL

Suppose we have three tables: Table 1|c_id|categories||-------------------|---------------- --||7|a||4|b||3|c|Table 2|c_id|dup_id||-------------------|---- ----------||9|10||5|3||6|2| Table 3|c_id|description||---------------- ---|--------

P粉151720173 2024-04-03 16:00:37 0  1  354

"Filter" huge MariaDB/Mysql tables based on different tables

Processing large datasets in my mariaDB database. I have two tables, Table A contains 57 million rows and Table B contains about 500 rows. Table B is a subset of ids related to columns in Table A. I want to delete all rows without corresponding ID in A table B. Example table A: classification_id nam...

P粉287345251 2023-09-07 10:51:26 0  2  595

Both tables in the join query have id auto-increment fields. After querying, which table's id will be displayed?

Both tables in the join query have id auto-increment fields. After querying, which table's id will be displayed? All the id fields I output become integers 1. How to solve this?

sui 2017-12-12 15:21:06 0  2  1119