Sql Developer Interview Questions
SQL stands for Structured Query Language, and SQL developers create SQL databases and the applications that work with them. They often use design tables and storing procedures for stability, reliability and performance. In an SQL developer interview, employers often ask questions about your programming knowledge and problem-solving skills.
Top SQL Developer Interview Questions & How to Answer
Here are three top SQL developer interview questions and tips on how to answer them:
Question No. 1: What are the types of keys in SQL and when would you use them?
How to answer: This question lets you demonstrate your knowledge of SQL. Discuss the most common types of SQL keys and talk about how they can identify rows and columns in tables. Keys work as unique identifiers, allowing users to retrieve data easily.
Question No. 2: What are the types of normalisation available in SQL and how do you use them?
How to answer: People use SQL normalisation to organise data and reduce redundancies. You can demonstrate your experience by discussing the normalisation methods you use the most. For example, many developers divide a large table into several smaller ones for easier readability.
Question No. 3: Which programming languages are you familiar with?
How to answer: Many SQL developers also use JavaScript, HTML, Python, PL/SQL and other languages. Mention the languages you know and how you used them at your previous job. Also, tell the interviewer about any programming certifications you received.
SQL - Trigger, Stored Procedure, SQL Basics, truncate & delete HR - Joins, Multirow functions
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Trigger is a kind of special stored procedure which will execute automatically when a when an event occures in database server. Less
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Stored procedure is a prepared SQL code which is saved for reusing.
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Truncate is similar to the delete command but it removes entire table. Delete is the command Which is used to remove some data by using where clause. Less
If I knew what the cross apply operator was
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If they want the word its join, a description could be "the Cartesian product of multiplying the tables" and an example would be "like merging two matrices except every column may be of incongruent variables creating a result with polynomial rows, (which is likely no longer normalized to the form level of the database)" Less
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An Apply operator is a join type that the query engine evaluates in sequential order because the right-hand table object can reference data in the left-hand table object. The Cross Apply operator is the Apply operator that acts like an Inner Join, eliminating any records in the left-hand table object that have a null match in the right-hand table object. Less
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An Apply operator is a join type that the DB engine evaluates in sequential order because the right-hand table object can reference data in the left-hand table object. The Cross Apply operator is the Apply operator that acts like an Inner Join, eliminating any records in the left-hand table object that have a null match in the right-hand table object. Less
Given 2 dates, return a result set that outputs a number for each week between the two. (They will ask the numbered week to be the sequential week and also the calendar week. Prepare for given start date to be start mid-week.)
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--Given 2 dates, return a result set that outputs a number for each week between the two. (They will ask the numbered week to be the sequential week and also the calendar week. Prepare for given start date to be start mid-week.) declare @temp date, @d date = '2020-01-01', @dd date = '2020-03-01', @i int = 0 declare @t table (w int, d date); declare @w int, @wp int = 0 set @temp = @d; while @temp @wp begin insert into @t values (@w, @temp) set @wp = @w end end select * from @t; Less
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--Given 2 dates, return a result set that outputs a number for each week between the two. (They will ask the numbered week to be the sequential week and also the calendar week. Prepare for given start date to be start mid-week.) declare @temp date, @d date = '2020-01-01', @dd date = '2020-03-01', @i int = 0 declare @t table (w int, d date); declare @w int, @wp int = 0 set @temp = @d; while @temp @wp begin insert into @t values (@w, @temp) set @wp = @w end end select * from @t; Less
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DECLARE @Start_Dt DATE = '2020-01-07', @End_Dt DATE = GETDATE(), @SequencialWeek_No INT = 1, @OldWeek_No INT = 0, @Week_No INT = 0; DROP TABLE IF EXISTS #Temp; CREATE TABLE #Temp ( Date DATE, Week_No INT, SequencialWeek_No INT ); WHILE @Start_Dt <= @End_Dt BEGIN SET @OldWeek_No = @Week_No; SET @Week_No = DATEPART(wk, @Start_Dt); SET @SequencialWeek_No = CASE WHEN @Start_Dt = '2020-01-07' THEN 1 WHEN @OldWeek_No = @Week_No THEN @SequencialWeek_No ELSE @SequencialWeek_No + 1 END; INSERT INTO #Temp ( Date, Week_No, SequencialWeek_No ) SELECT @Start_Dt, @Week_No, @SequencialWeek_No; SET @Start_Dt = DATEADD(DAY, 1, @Start_Dt); END; SELECT * FROM #Temp ORDER BY Date; Less
What is the result if we do following Null + 90
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Always remember null + anything will be null. Also applicable for - ,* ,/
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Null
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Null .anything+ null is null
Not unexpectedly, the manager was particularly interested in my experience in gathering requirements and creating designs.
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What kind of design excersice did you have to present? something related to data modelling? I'm just curious Less
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It was a high-level design for a loan application, including the architecture and data model for the application. Less
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Because I had 12 years as team lead on a top priority application, I had good stories to relate about my experience gathering requirements and creating designs. Less
Delete duplicate records from a table
2 Answers↳
referr google
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Do they ask to write a program or only sql queries?
What's the difference between TRUNCATE and DELETE
2 AnswersHow to retrieve unique rows from database without using Distinct or Unique keyword
2 Answers↳
One of the method is select a ROWID among duplicate columns
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One method is to use GROUP BY the column(s) you want as distinct.
how to retrieve first five rows from database.
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select top 5* from table;
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SELECT *FROM table_name ORDER BY column_name_id LIMIT 5;
how to transform a string into comma separated values
2 Answers↳
use split()
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Listtag(string,delimeter)