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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

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 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "A

4 Built-in functions in SQL Explained Superbly

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Here're four types of built-in functions in SQL. You don't need to create these functions, and these come with your SQL. I am discussing today the  SQL functions List . SQL functions DATE-TIME functions Numeric functions Char functions Null-related functions 1. DATE-TIME functions   These are useful to get DATE and Time. Also, you can covert the DATE and TIME to Char. These are TO_CHAR, CURRENT_DATE, and CURRENT_TIME. 2. Numeric Functions   These functions you can use for numeric calculations. Those are TRUNC, SIGN, ROUND, ABS. 3. Char Functions   To handle string-related tasks you can use CHAR functions. The CHAR functions are like SUBSTR, CONCAT, LENGTH. 4. NULL related functions   To handle null values you can use different functions. Those are COALESCE, NVL, NULLIF This post covered all your answers for the SQL functions list, SQL built-in functions in Oracle, and SQL functions in any DBMS. Also, Read SQL tips to improve Query performance Summar