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Articles on Trending Technologies
Technical articles with clear explanations and examples
Cursors in Oracle DBMS
When a SQL statement is executed in Oracle, the temporary context area is created. This area contains all the relevant information relating to the statement and its execution. The cursor is a pointer to this context area and allows the PL/SQL program to control this area.There are two types of Cursors.Implicit CursorsExplicit CursorsLet us begin with Implicit Cursors −Implicit CursorsWhenever an SQL statement is executed, the implicit cursors are automatically created. This happens if there is no explicit cursor for the particular statement. Implicit cursors cannot be controlled by the programmers.There are many different attributes for Implicit Cursors. Some of ...
Read MoreIn MySQL, how FIELD() function is different from FIND_IN_SET() function?
As we know, both the functions are used to search a string from the arguments provided in them but there are some significant differences between them as follows −FIND_IN_SET() − function uses the string list that is itself a string containing the substring separated by commas. Whereas, FIELD() function contains list of different strings among which it will find the index number of the string, if present, which is to be searched.FIND_IN_SET() − function returns NULL if any of the argument i.e. either search string or string list is NULL. In contrast, FIELD() function do not returns NULL but returns ...
Read MoreDDBMS Components
The contents of a distributed database are spread across multiple locations. That means the contents may be stored in different systems that are located in the same place or geographically far away. However, the database still appears uniform to the users i.e the fact that the database is stored at multiple locations is transparent to the users.The different components of a distributed database are −Let us now discuss them one by one −UsersThere are many users who use the distributed database. For them, the fact that the database is spread across multiple locations is transparent and they perceive the database ...
Read MoreWhat MySQL ELT() function returns if the index number, provided as an argument, is higher than the number of strings?
MySQL ELT() function returns NULL as output if the index number provided as argument is higher than the number of strings. Following is an example to make it clearer −Examplemysql> Select ELT(6,'Ram','is','a','good','boy')As Result; +--------+ | Result | +--------+ | NULL | +--------+ 1 row in set (0.00 sec)As we can see that index number is 6 and the list of strings is having only 5 strings. Hence MySQL returns NULL.
Read MoreWhen MySQL FIND_IN_SET() function returns NULL as output?
FIND_IN_SET() function returns NULL as output if any of the argument i.e. either search string or string list, is NULL. Of course, It will also return NULL if both of the arguments are NULL.Examplemysql> Select FIND_IN_SET(NULL,'Ram is a good boy') AS Result; +--------+ | Result | +--------+ | NULL | +--------+ 1 row in set (0.00 sec) mysql> SELECT FIND_IN_SET('RAM',NULL)AS RESULT; +--------+ | RESULT | +--------+ | NULL | +--------+ 1 row in set (0.00 sec) mysql> SELECT FIND_IN_SET(NULL,NULL); +------------------------+ | FIND_IN_SET(NULL,NULL) | +------------------------+ | NULL | +------------------------+ 1 row in set (0.00 sec)
Read MoreOverview of Packages in Oracle
Packages are SQL procedures, functions, variables, statements etc. that are grouped into a single unit. Many different applications can share the contents of a package, as it is stored in the database.Parts of a PackageThe following are the parts of a package in Oracle −Package SpecificationThe package specifications contains information about all the procedures, functions, variables, constants etc. stored inside it. It has the declaration of all the components but not the code.All the objects that are in the specification are known as public objects. If there is any object that is not available in the specification but is coded ...
Read MoreWhat MySQL returns if the search string, provided in FIELD() function, is NULL?
As we know that NULL fails equality comparison with any value hence if the search string, provided in FIELD() function, is NULL then MySQL returns 0 as output.Examplemysql> Select FIELD(NULL,'Ram','is','good','boy'); +-------------------------------------+ | FIELD(NULL,'Ram','is','good','boy') | +-------------------------------------+ | 0 | +-------------------------------------+ 1 row in set (0.00 sec)
Read MoreWhat MySQL returns if the search string is not in the list of strings provided as argument in FIELD() function?
Suppose if the search string is not in the list of strings provided as the arguments in FIELD() function then MySQL will return 0 as output.Examplemysql> Select FIELD('Ram','New','Delhi'); +----------------------------+ | FIELD('Ram','New','Delhi') | +----------------------------+ | 0 | +----------------------------+ 1 row in set (0.00 sec)
Read MoreWhat MySQL returns if we use NULL, as both the arguments, as one of the argument and as a separator, in CONCAT_WS() function?
NULL as both argumentsMySQL returns blank output if we will use NULL as both of the arguments in CONCAT_WS() function.Examplemysql> Select CONCAT_WS('', NULL, NULL); +-------------------------+ | CONCAT_WS('', NULL, NULL) | +-------------------------+ | | +-------------------------+ 1 row in set (0.00 sec)NULL as one of the argumentMySQL returns the value of the other argument as output if we will use NULL as one of the argument in CONCAT_WS() function.Examplemysql> Select CONCAT_WS('', NULL, 'Delhi'); +----------------------------+ | CONCAT_WS('', NULL, 'Delhi') | +----------------------------+ | Delhi ...
Read MoreWhat is the maximum length of data we can put in a TEXT column in MySQL?
As we know TEXT data objects are useful for storing long-form text strings. The different TEXT objects offer a range of storage space from 255 bytes to 4 Gb. The following table shows the storage of different kinds of TEXT data type −Type of BLOBMaximum amount of Data that can be storedOverheadTINYTEXTUp to 255 bytes1 byteTEXTUp to 64 Kb2 bytes MEDIUMTEXTUp to 16 Mb3 bytesLONGTEXTUp to 4 Gb4 bytes
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