I have 3 tables with name USER, SCORE and LEVEL as given below. From these tables, I’m trying to prepare a scoreboard, in which each user will be arranged based on their level, and score. And for each user, only highest level and corresponding highest score in that level will be shown. I have written a …
Tag: mysql
What is Difference Between AND,OR operator in MYSQL ,While Retrieving the Rows?
Are there difference between these queries and how they execute? Answer It’s to do with intersecting truth tables. In the first query the or is inside brackets so it will execute first and return true if the country is either USA or France. Then the And will execute and compare the result of the OR to t…
How to prevent SQL injection in Question2Answer?
I want to prevent SQL injection in Question2Answer. This is how I store data in MySQL via HTML form. I know it’s a security risk. Examples – OR and SQL query is – How should I post data in the latest PHP 7 and above version? I think escaping strings is deprecated or outdated. Answer Based on…
While display group of table value in mysql it shows each and every value as ‘0’
my table and it’s values are Now, i am going to grouping table but returns value in 0 While group the table it returns each and every column value returns in 0. Why that is happened. I need present or absent instead of 0. Can anyone solve this logic error? Answer sum(case when hour = ‘P1’ th…
Designing a mysql database of relationships between contacts?
I’m trying to design a database of contacts but I also want to keep track of their relationships with other contacts whether it be family, friends, cowokers etc. I created a table for contacts and created an affiliates table that labels the type of relationship but I’m not sure if I did the design…
How do I retrieve data from two tables?
I was on the “hospital_payment_data” table. I want to call up the data of the number of data, the cache_account_received sum, and the total_medical_bills sum, and then bring up the mount sum value …
Why MariaDB refuses to create a simple table with error [42000][1064]?
I just want to know how to fix this, or why MariaDB server keeps me returning an error. I just install the database, create a user, a new schema, I’m pointing to that database with use database testing; and I’m ready to create a simple table on a database with this query: The user in the database …
How to view the Create Table SQL command after a table has been created in mySQL phpMyAdmin
When you create a mySQL table using the GUI in phpAdmin there is an option to preview the SQL create table command. Once you have created a table, made adjustments and finalised the structure, is it possible to review the SQL create command for the current version of the table? Answer SHOW CREATE TABLE Shows …
MySQL:How to Rewrite a Select element as ‘y’ then using that later in a where statement
So what im trying to do is this but this doesn’t work: Here is another example: Answer You can’t use an aggregate expression (sum(), count(), …) in the where clause of the query. This clause is evaluated before rows are grouped together by the group by clause, so the aggregates are not yet a…
Retrieving pictures from MySQL using Java
I have a question related to retrieving files from MySQL using JDBC. I managed to save a .png file from my desktop & retrieve it successfully, but I can’t read the file. It shows that the format …