logo
down
shadow

Joins without foreign key


Joins without foreign key

Content Index :

Joins without foreign key
Tag : mysql , By : kbrust
Date : January 12 2021, 08:33 AM

Hope this helps Yes and no depending on how data gets in to those tables.
Yes, if records in the second table will always be created after the first (ie the second tables data is some information that will come later)

Comments
No Comments Right Now !

Boards Message :
You Must Login Or Sign Up to Add Your Comments .

Share : facebook icon twitter icon

Foreign Keys vs Joins


Tag : sql , By : jaime
Date : March 29 2020, 07:55 AM
this one helps. Foreign keys are just constraints to enforce referential integrity. You will still need to use JOINs to build your queries.
Foreign keys guarantee that a row in a table order_details with a field order_id referencing an orders table will never have an order_id value that doesn't exist in the orders table. Foreign keys aren't required to have a working relational database (in fact MySQL's default storage engine doesn't support FKs), but they are definitely essential to avoid broken relationships and orphan rows (ie. referential integrity).

Rails where joins for different foreign key


Tag : ruby-on-rails , By : Stephen Judge
Date : March 29 2020, 07:55 AM
help you fix your problem The employees table isn't being aliased as super, and doesn't need to be aliased at all in this case since it's only joined one time:
workorders = workorders.joins(:client,:super).
               where("wonum like :search or description like :search or clients.client_name like :search or employees.employee_full_name like :search ", 
               search: "%#{params[:sSearch]}%")
scope :search, lambda{ |term|
  %w(wonum description clients.client_name employees.employee_full_name).
    map{|field| "#{field} like :search" }.
    join(" or "), search: term
}

workorders = workorders.joins(:client, :super).search("%#{params[:sSearch]}%")

SQL. Re: inner joins & foreign keys


Tag : asp.net , By : jch
Date : March 29 2020, 07:55 AM
hop of those help? First, inner join is how you get your tables "back together", and @SpectralGhost's example is how you do it. But you might want to consider doing it in the database rather than in your ASP code. The way you do that is with views. If you create a view (the syntax is CREATE VIEW and there are plenty of examples out there) then you can make the database schema as complex as you need to without making it hard to use in your ASP application. You can even make views updatable (you define an "INSTEAD OF" trigger, again, many examples if you search).
But you probably don't want to update a view, or a table, directly from your ASP code. You probably want to define STORED PROCEDUREs that update your data, and call those from your ASP code. This allows you to restrict access to your tables and views to read only and force any writes to come through a stored procedure you can control better. This prevents SQL INJECTION, making your ASP application much more secure. If the service account the application pool you ASP page runs under can pass raw queries to the database then any compromise can do tremendous damage to your database. If all it can do is execute a stored procedure where the parameters can be changed but not the functionality, they can only put some junk values in, or maybe not even that if you range check well.

Foreign Key Types on Joins


Tag : sql-server , By : Adam May
Date : March 29 2020, 07:55 AM
I wish did fix the issue. The main factor in the performance of an equality comparison (that does not involve type casting or converting) is the size of the datatype. The integer types in SQL Server have fixed sizes (4 bytes for an int, 8 bytes for a bigint, etc. - refer to the documentation for the full details), so the actual data is inconsequential. Varchars, on the other hand (and as opposed to chars), vary in their size depending on the size of the data (see the docs for details), so having shorter data may indeed affect a query's performance, but you'll have to have a pretty large number of rows to notice any difference.

Joins using foreign key codeigniter


Tag : codeigniter , By : user185751
Date : March 29 2020, 07:55 AM
like below fixes the issue The simplest query to get the data you want it using a join. Instead of using Query Builder I will use db->query()
public function absence(){
    $id2= $this->session->CNE;
    $query = $this->db->query("Select * From absence_etudiant Inner Join absence On absence.id_absence = absence_etudiant.CNE Where absence_etudiant.CNE = $id2");

    $data['absences'] = $query->result();
    $this->load->view('Etudiants/affi', $data);
}
  <table> 
    <?php foreach($absences as $absence) : ?>
      <tr> 
        <td><strong><?php echo $absence->id_absence; ?></strong></td>
        <td><?php echo $absence->id_seance; ?></td>
        <td><?php echo $absence->justification; ?></td>
        <td><?php echo $absence->course; ?></td>
      </tr>
    <?php endforeach; ?>
  </table>
Related Posts Related QUESTIONS :
  • date type casting in npm package?
  • GROUP BY a, b VS GROUP BY b, a
  • How to store multiple values on a mysql table
  • 2 SELECT in a query with ORDER BY
  • BigQuery: How to run cohort / retention analysis for userbase across 2.5 years?
  • Can't connect local database. Sequel Pro encountered an unexpected error
  • How do I change the auto increment counter in MySQL from +1 to +43
  • How to query non duplicate rows but keep the primary key
  • How to group all scores by username in a table and display rank?
  • How to remove timestamp with the date using sql query?
  • Modify SQL query to get data only from past 2 months
  • change engine type from MyISAM to InnoDB
  • Need mysql query to find total sum as per matched query
  • json_table syntax and structure
  • Is there any way in sql query to rank certain value in ordered set of records such that ranking reset after it encounter
  • not able to login in google cloud storage sql instance
  • Inserting data into MySQL database with VBA
  • Make (user_id&music_id) unique in Likes table and Dislikes table
  • Can't do 50k insertion using bulkCreate
  • SQL syntax to get data IN date
  • How to get 4-byte emojis to store correctly in mysql 5.7?
  • How to create an in-memory database for PHPUnit testing?
  • How to write an SQL query to fetch the id in a column that has all the required data in some other column?
  • Invalid COLUMN in the select list because it is not contained in either an aggregate function or the GROUP BY clause
  • How to get actual index number of rows in MySQL when using Where clause
  • SQL Table Relationship
  • How to fix "FUNCTION doesnt exist" error in mysql?
  • Importing .bak from MSSQL into MySQL database
  • Aggregate query with distinct subquery kills every connection
  • How do i use and with multiple or condition?
  • How to fix 'The server requested authentication method unknown to the client [caching_sha2_password]' on docker compose?
  • In Mysql How to fetch distinct row value from a column1 and sum(column 2 row value) group by invoice number
  • MySQL ORDER BY field with a toggle
  • How to insert system's Date into Table
  • Aws lambda function too many connection issue rds
  • MYSQL - join 2 tables - sort in time
  • SQL code to select records where field_A matches the field_A value of a certain field_B value
  • How to model Amazon Redshift external table for changing column structure?
  • Query the list of CITY names from STATION that do not start with vowels and do not end with vowels. Your result cannot c
  • how to get rows with time for each minute for last 30 minutes
  • SQL Query With Between ,AND & OR in Where Clauses Not Given Correct Answers
  • ER_PARSE_ERROR: You have an error in your SQL syntax;
  • How to write normal sql queries inside controller in laravel
  • MySql query between range values(single record)
  • Set length conditions on text column in MySQL table
  • Mysql order of sorting
  • Sequelize raw queries TextRow and getting data out of it
  • Comparing the contents of two csv files, where the relation between the two files is specified in a third file?
  • Can 1 primary id link to multiple ids in one table?
  • Rewrite MySQL query and make it short
  • Why are parentheses used in JOIN USING clauses
  • Delete from row to row in phpadmin
  • Inserting Data into a table
  • How to efficiently get a entry with highest version in mysql table
  • How do I create views in dolphindb?
  • MySQL - update with inner join is creating nulls
  • Should i rather use a subquery or a combined WHERE?
  • INSERT INTO using data from other table causing ERROR 1064
  • How to display a MySQL table completely?
  • Can create procedure without using delimiter in MySQL?
  • shadow
    Privacy Policy - Terms - Contact Us © scrbit.com