SEQUENCE Sequence is a database object and users use this to genearte unique integer numbers randomly. When a sequence no is generated, the sequence no is incremented independent of transaction committing or rooling back. so if the transaction is rolled back there would be missing sequence no in table. To create a Sequence in own …
Aggregate Functions: AVG AVG returns average value of Expression Ex: AVG(salary) CORR CORR returns the corelation of a number pair CORR(exp1,exp2) COUNT COUNT returns no of rows returned by a query EX: select COUNT(*) from employee; COVAR_POP COVAR_POP returns the population covariance of a set of number pairs COVAR_POP(xi,yi) CUME_DIST CUME_DIST calculates the cumulative distribution …
Delete Truncate Delete is a DML statement Truncate is a DDL statement Deletes all data or based on condition and needs an explicit commit or rollback Removes all data from table and commit/rollback not required Data can be rolledback. Data can’t be rolled back. Truncate deletes data permanently You can use condition(Where clause) in Delete …
This post provides an introduction to following concepts : Hadoop Basics What is HDFS ? What is YARN ? Lets start with the simplest question first. What is Big Data ? Big data is a term coined for huge volume of data(in terrabytes or petabytes) that is difficult to manage using traditional DBMS. Here are …
Conversion functions ASCIISTR(s) Returns the ASCII equivalent of all characters in the string s. CAST(expr AS type) Converts the expression expr into datatype type. The expr can be an expression, subquery, or MULTISET clause. See the possible conversion table for standard datatypes. CHARTOROWID(s) Returns the string s as a ROWID datatype. …