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To Copy Data from a CSV file to a table COPY <tablename> FROM '<filename with path>'; To insert into table user from a file named user_data.csv placed inside /home/user/: COPY user FROM '/home/user/user_data.csv'; To Copy data from pipe separated file to table COPY user FROM '/h...

To Copy table to standard o/p COPY <tablename> TO STDOUT (DELIMITER '|'); To export table user to Standard ouput: COPY user TO STDOUT (DELIMITER '|'); To Copy table to file COPY user FROM '/home/user/user_data' WITH DELIMITER '|'; To Copy the output of SQL statement to file COPY (sql st...

Data can be exported using copy command or by taking use of command line options of psql command. To Export csv data from table user to csv file: psql -p \<port> -U \<username> -d \<database> -A -F<delimiter> -c\<sql to execute> \> \<output filename with path&gt...

You can use using in order to set an alias for a namespace or type. More detail can be found in here. Syntax: using <identifier> = <namespace-or-type-name>; Example: using NewType = Dictionary<string, Dictionary<string,int>>; NewType multiDictionary = new NewType(); /...

You can test for IndexedDB support in the current environment by checking for the presence of the window.indexedDB property: if (window.indexedDB) { // IndexedDB is available }

Opening a database is an asynchronous operation. We need to send a request to open our database and then listen for events so we know when it's ready. We'll open a DemoDB database. If it doesn't exist yet, it will get created when we send the request. The 2 below says that we're asking for version...

If you want to connect to an HBase server, first you need to make sure that the IP of the server is in your /etc/hosts file for example add the line 255.255.255.255 hbase Then you can use the Java API to connect to zookeeper, you only have to specify the client port and the zookeeper address ...

In HBase, data are stored in tables with columns. Columns are regrouped in column families, which can be for example "personal" or "professional", each of these containing specific informations. To create a table, you need to use the Admin Object, create it using : Admin admin ...

In HBase, you can use 4 types of operations Get : retrieves a row Put : inserts one or more row(s) Delete : delete a row Scan : retrieves several rows If you simply want to retrieve a row, given its row_key you can use the Get object: Get get = new Get(Bytes.toBytes("my_row_key")...

Basically, the Scan object retrieves all the rows from the table, but what if you want to retrieve only the rows where the value of a given column is equal to something ? Let me introduce you the Filters, they work like the WHERE in SQL. Before starting using the filters, if you know how your row_k...

There are two ways to define an anonymous function: the full syntax and a shorthand. Full Anonymous Function Syntax (fn [x y] (+ x y)) This expression evaluates to a function. Any syntax you can use with a function defined with defn (&, argument destructuring, etc.), you can also do with wi...

(defn print-some-items [[a b :as xs]] (println a) (println b) (println xs)) (print-some-items [2 3]) This example prints the output 2 3 [2 3] The argument is destructured and the items 2 and 3 are assigned to the symbols a and b. The original argument, the entire vector [2 ...

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In the node JS command prompt, inside your loopback project, type the following command to create a new model. slc loopback:model If you have installed LoopBack CLI tool, you can create model with: lb model The command prompt will request informations about the model to create. In this examp...

Once you are done with a worker you should terminate it. This helps to free up resources for other applications on the user’s computer. Main Thread: // Terminate a worker from your application. worker.terminate(); Note: The terminate method is not available for service workers. It will be term...

console.dir(object) displays an interactive list of the properties of the specified JavaScript object. The output is presented as a hierarchical listing with disclosure triangles that let you see the contents of child objects. var myObject = { "foo":{ "bar":"d...

How To Install ANTLR in Eclipse (Last tested on Indigo and ANTLR IDE 2.1.2) Install Eclipse. Download ANTLR complete binaries jar that includes ANTLR v2. Extract to a temp directory. Copy the antlr-n.n folder to an appropriate permanent location, for example the same folder that Eclipse is in...

Server Syntax var io = require('socket.io')(80); io.on('connection', function (mysocket) { //custom event called `private message` mysocket.on('private message', function (from, msg) { console.log('I received a private message by ', from, ' saying ', msg); }); //internal `di...

Suppose we want to read and stack a bunch of similarly-formatted files. The quick solution is: rbindlist(lapply(list.files(patt="csv$"), fread), id=TRUE) We might not be satisfied with this for a couple reasons: It might run into errors when reading with fread or when stacking with ...

Specifies custom foreign key name if a foreign key not following EF's convention is desired. public class Person { public int IdAddress { get; set; } [ForeignKey(nameof(IdAddress))] public virtual Address HomeAddress { get; set; } } This can also be used when you have multipl...