Random Testing Flashcards
How many TRIGGERS are allowed in MySql table?
BEFORE INSERT AFTER INSERT BEFORE UPDATE AFTER UPDATE BEFORE DELETE and AFTER DELETE
What does a TIMESTAMP do on UPDATE CURRENT_TIMESTAMP data type?
TIMESTAMP column is updated with Zero when the table is created. UPDATE CURRENT_TIMESTAMP modifier updates the timestamp field to the current time whenever there is a change in other fields of the table.
What is InnoDB?
lnnoDB is a transaction safe storage engine developed by Innobase Oy which is a Oracle Corporation now.
What are federated tables?
Federated tables which allow access to the tables located on other databases on other servers.
What are the column comparisons operators?
The = , <>, <=, =, >,<>, <=>, AND, OR, or LIKE operators are used in column comparisons in SELECT statements.
How do you control the max size of a HEAP table?
Maximum size of Heal table can be controlled by MySQL config variable called max_heap_table_size.
What is the difference between mysql_fetch_array and mysql_fetch_object?
Following are the differences between mysql_fetch_array and mysql_fetch_object: mysql_fetch_array() -Returns a result row as an associated array or a regular array from database. mysql_fetch_object – Returns a result row as object from database.
What are all the Common SQL Function?
CONCAT(A, B) – Concatenates two string values to create a single string output. Often used to combine two or more fields into one single field. FORMAT(X, D) – Formats the number X to D significant digits. CURRDATE(), CURRTIME() – Returns the current date or time. NOW() – Returns the current date and time as one value. MONTH(), DAY(), YEAR(), WEEK(), WEEKDAY() – Extracts the given data from a date value. HOUR(), MINUTE(), SECOND() – Extracts the given data from a time value. DATEDIFF(A, B) – Determines the difference between two dates and it is commonly used to calculate age SUBTIMES(A, B) – Determines the difference between two times. FROMDAYS(INT) – Converts an integer number of days into a date value.
What storage engines are used in MySQL?
Storage engines are called table types and data is stored in files using various techniques. Technique involves: Storage mechanism Locking levels Indexing Capabilities and functions.
What is ISAM?
ISAM is abbreviated as Indexed Sequential Access Method.It was developed by IBM to store and retrieve data on secondary storage systems like tapes.
What is the difference between BLOB AND TEXT?
The only difference between BLOB and TEXT types is that sorting and comparison is performed in case-sensitive for BLOB values and case-insensitive for TEXT values.
How many columns can be used for creating Index?
Maximum of 16 indexed columns can be created for any standard table.
What are the different tables present in MySQL?
MyISAM Heap Merge INNO DB ISAM
What is the default port for MySQL Server?
The default port for MySQL Server is 3306. Another standard default is port 1433 in TCP/IP for SQL Server.
How to display top 50 rows?
SELECT * FROM LIMIT 0,50;
What does myisamchk do?
It compresses the MyISAM tables, which reduces their disk or memory usage.
What do you mean by % and _ in the LIKE statement?
% corresponds to 0 or more characters, _ is exactly one character in the LIKE statement.
What is the difference between primary key and candidate key?
Every row of a table is identified uniquely by primary key. There is only one primary key for a table. Primary Key is also a candidate key. By common convention, candidate key can be designated as primary and which can be used for any foreign key references.
What are the drivers in MySQL?
PHP Driver JDBC Driver ODBC Driver C WRAPPER PYTHON Driver PERL Driver RUBY Driver CAP11PHP Driver Ado.net5.mxj
Can you tell what are the different set operations available in MySQL?
UNION – This operation returns all the distinct rows selected by a query
UNION ALL – This operation returns all the rows selected by a query and also includes all duplicate rows.
MINUS – This operation returns all the distinct rows selected by the first query but does not select the rows selected by the second query.
INTERSECT – This operation returns all the distinct rows selected by both queries.
Can you tell the order of SQL SELECT statement?
The order of SQL SELECT statement is as follows:
SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY.
Can you tell how can you display the Maximum salary in SQL?
To display the maximum salary in SQL, you can use the inbuilt function called MAX().
Can you tell how many values can Set the function of MySQL to consider?
MySQL’s Set function can take a maximum of 64 values, but can also consider 0 values.
