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Database Articles
Page 437 of 546
What is the use of setFetchSize() and setMaxRows() methods of the JDBC Statement Interface?
The setFetchSize(int) method defines the number of rows that will be read from the database when the ResultSet needs more rows. setFetchSize(int) affects how the database returns the ResultSet data.Whereas, setMaxRows(int) method of the ResultSet specifies how many rows a ResultSet can contain at a time. setMaxRows(int) affects the client side JDBC object.
Read MoreWhat is JDBC Clob data type? how to store and read data from it?
CLOB stands for Character Large Object in general, an SQL Clob is a built-in datatype and is used to store large amount of textual data. Using this datatype, you can store data up to 2, 147, 483, 647 characters.The java.sql.Clob interface of the JDBC API represents the CLOB datatype. Since the Clob object in JDBC is implemented using an SQL locator, it holds a logical pointer to the SQL CLOB (not the data).MYSQL database provides support for this datatype using four variables.TINYTEXT: A CLOB type with a maximum of 28-1 (255) characters.TEXT: A CLOB type with a maximum of 216-1 ...
Read MoreHow to know which storage engine is used in MongoDB?\\n
To know which storage engine is used in MongoDB, you can use storageEngine. The syntax is as follows −db.serverStatus().storageEngine;To know all the configuration details of storage engine, you can use the following syntax:db.serverStatus().yourStorageEngineName;Let us implement the above syntax to know which storage engine is being used in MongoDB. The query is as follows −> db.serverStatus().storageEngine;The following is the output −{ "name" : "wiredTiger", "supportsCommittedReads" : true, "supportsSnapshotReadConcern" : true, "readOnly" : false, "persistent" : true }In order to know all configuration details about the above storage engine, the query is as follows −> db.serverStatus().wiredTiger;The following ...
Read MoreHow to check the current configuration of MongoDB?
In order to check the current configuration of MongoDB, you can use getCmdLineOpts. The query is as follows −> db._adminCommand( {getCmdLineOpts: 1});The following is the output −{ "argv" : [ "mongod" ], "parsed" : { }, "ok" : 1 }In order to check live settings, you can use the below query −> db._adminCommand({getParameter:"*"});The following is the output &minus{ "AsyncRequestsSenderUseBaton" : true, "KeysRotationIntervalSec" : 7776000, "ShardingTaskExecutorPoolHostTimeoutMS" : 300000, "ShardingTaskExecutorPoolMaxConnecting" : 2, "ShardingTaskExecutorPoolMaxSize" : -1, "ShardingTaskExecutorPoolMinSize" : 1, "ShardingTaskExecutorPoolRefreshRequirementMS" : 60000, "ShardingTaskExecutorPoolRefreshTimeoutMS" : 20000, "TransactionRecordMinimumLifetimeMinutes" : 30, "adaptiveServiceExecutorIdlePctThreshold" : 60, "adaptiveServiceExecutorMaxQueueLatencyMicros" ...
Read MoreHow to get connected clients in MongoDB?
To get connected clients in MongoDB, use currentOp() with the set value to true and you need to iterate array result set with the help of field client. Let us first implement currentOp> db.currentOp(true)Following is the output. Here the client is 127.0.0.1 since we are using localhost. The output displays all the connected clients{ "inprog" : [ { "host" : "DESKTOP-QN2RB3H:27017", "desc" : "conn1", "connectionId" : 1, "client" : "127.0.0.1:61787", "appName" : "MongoDB Shell", ...
Read MoreWrite a MySQL query equivalent to “SHOW TABLES” in sorted order?
Use INFORMATION_SCHEMA.TABLES to display tables in sorted order. The below syntax will give sorted list of tables in ascending order:select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA= 'yourDatabaseName' order by TABLE_NAME;Following is the query to implement the equivalent to SHOW TABLES:mysql> select TABLE_NAME from INFORMATION_SCHEMA.TABLES -> where TABLE_SCHEMA= 'sample' order by TABLE_NAME;This will produce the following output+------------------------------------+ | TABLE_NAME | +------------------------------------+ | a | | accumulateddemo ...
Read MoreWhat is the alias to Show Tables in MySQL Result?
You can use AS command for alias to show tables in MySQL result. Following is the syntax −SELECT TABLE_NAME AS anyAliasName FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = DATABASE();Let us implement the above syntax −mysql> SELECT TABLE_NAME AS MY_TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = DATABASE();This will produce the following output −+------------------------------------+ | MY_TABLE_NAME | +------------------------------------+ | a | | accumulateddemo | | add10minutedemo ...
Read MoreWhat does /* in MySQL means?
This is a type of comment. The /* is the beginning of a comment and */ is the end of comment.Let us implement and display how to create a commentmysql> /* This is the first MySQL Program */MySQL will ignore the above comment.Let us see an example. Here, we have written a comment with /* and */mysql> /*This table has information about person */ mysql> create table DemoTable ( PersonId int NOT NULL AUTO_INCREMENT PRIMARY KEY, PersonName varchar(20), PersonAge int ); Query OK, 0 rows affected (0.58 sec)
Read MoreRun SQL file in MySQL database from terminal?
To run SQL file in database, you need to use below syntax:mysql -u yourUserName -p yourDatabaseName < yourFileName.sqlTo understand the above syntax, let us open command prompt using windows+R shortcut key.The snapshot is as follows:After pressing OK button, you will get a command prompt. The snapshot is as follows:Now reach the bin directory, the snapshot is as follows:Here is my file ‘mydb.sql’ which is located in bin directory. The snapshot and content of SQL file is as follows:Now you can type the above syntax which I have discussed to run SQL file. The snapshot of command is as follows:Now you ...
Read MoreImplement MySQL INSERT MAX()+1?
You need to use COALESCE() function for this. The syntax is as follows:INSERT INTO yourTableName(yourColumnName1, yourColumnName2) SELECT 1 + COALESCE((SELECT MAX(yourColumnName1) FROM yourTableName WHERE yourColumnName2=’yourValue’), 0), ’yourValue’;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table InsertMaxPlus1Demo -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (1.27 sec)Now you can insert some records in the table using insert command. The query is as follows:mysql> insert into InsertMaxPlus1Demo(Id, Name) values(1, 'John'); Query OK, 1 row affected (0.12 sec) mysql> insert ...
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