Found 22 Articles for PostgreSQL

How to Remove Unicode from Jenkins Console Output logs using Postman?

Debomita Bhattacharjee
Updated on 03-Aug-2021 14:07:22
We can remove Unicode from Jenkins Console Output logs. To perform this, we should create a Collection with at least a single request. Along with it, we have to install Newman.Step 1 − Click on the arrow appearing to the right of the name of the Collection. After that, click on Share.Step 2 − SHARE COLLECTION pop-up shall open. Navigate to the Get public link tab and copy the link which is pointed out in the below image.Please note − The link obtained is specific to a particular user.Step 3 − Launch Jenkins and go to the Jenkins Job which ... Read More

Difference Between MySQL and PostgreSQL

Updated on 25-Mar-2021 06:28:38
In this post, we will understand the difference between MySQL and PostgreSQL.MySQLIt is a relational database management system.It is the product developed by Oracle Corporation.It is supported by Windows, Mac OS X, Linux, BSD, UNIX, z/OS, Symbian, AmigaOS.It can’t be extended.In this system, the phpMyAdmin tool gives the GUI.Mysqldump and XtraBackup provide backup in MySQL.It provides temporary table.It doesn’t provide a materialized view.It doesn’t provide Data Domain Object to the system.PostgreSQLIt is an object-relational database management system.It was developed by the Global Development Group.It is supported by Windows, Mac OS X, Linux and BSD but not by UNIX, z/OS, Symbian, ... Read More

Create Primary Key on an existing table in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 13:09:44
Although quite infrequent, you may come across situations wherein you need to define the primary key on an existing table. This can be achieved using the ALTER TABLE statement.The syntax is −ALTER TABLE table_name ADD PRIMARY KEY (column_name1, column_name2, …., columns_nameN)As can be seen from the above syntax, you can define PRIMARY KEY on multiple columns. When you have defined the PRIMARY KEY on multiple columns, the condition is that the column pairs should have unique and non-null values. Thus, if the PRIMARY KEY is defined on (column1, column2), the values (value1, value2), (value3, value2), and (value1, value4) are allowed. ... Read More

Extract day, hour, minute, etc. from a datetime column in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 13:08:17
Let us create a new table containing a single timestamp column −CREATE TABLE timestamp_test(    ts timestamp );Now let us populate it with some data −INSERT INTO timestamp_test(ts) VALUES(current_timestamp), (current_timestamp+interval '5 days'), (current_timestamp-interval '18 hours'), (current_timestamp+interval '1 year'), (current_timestamp+interval '3 minutes'), (current_timestamp-interval '6 years');If you query the table (SELECT * from timestamp_test), you will see the following output −ts2021-01-30 19:23:24.0080872021-02-04 19:23:24.0080872021-01-30 01:23:24.0080872022-01-30 19:23:24.0080872021-01-30 19:26:24.0080872015-01-30 19:23:24.008087Now, in order to extract hour, minute, etc. from the timestamp column, we use the EXTRACT function. Some examples are shown below −SELECT EXTRACT(HOUR from ts) as hour from timestamp_testOutput −hour19191191919Similarly −SELECT EXTRACT(MONTH from ts) as ... Read More

Aliasing in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 13:05:41
Often, we have some very long table names, and writing the table name every time is troublesome. We can use aliasing to help us there, thanks to which, we will need to write the long table name only once.The table aliases are generally written in the FROM part of the statement, or the JOIN part.For example, consider that we have two tables, marks, and student_info, defined respectively below −marksnameroll_noperc_marksAniket1224Siddhi4565Yash2642Isha5687student_infonameroll_noagegenderAniket1226MIsha5625FSiddhi4523FYash2625MNow, if you want to see the name, roll_no, perc_marks, and age of the student in one query, your query will look like this −SELECT, marks.roll_no, marks.perc_marks, student_info.age FROM marks LEFT ... Read More

How to combine different columns of a table to yield a single column in query output in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 13:02:48
Suppose you have a table user_info that contains the state and district of different users. An example is given below −namedistrictstateAnilMumbaiMaharashtraJoyJhalawarRajasthanRonPuneMaharashtraReenaMeerutUttar PradeshNow, if you want to combine the state and district in a single field called location, this is how you should be able to do it −SELECT name, district || ', ' || state as location from user_infoThe || operator is the string concatenation operator. The output will be −namelocationAnilMumbai, MaharashtraJoyJhalawar, RajasthanRonPune, MaharashtraReenaMeerut, Uttar PradeshSimilar operations can also be performed on numerical values. Suppose you have a table marks containing the total marks scored by students and the maximum ... Read More

How to look for partial string matches in queries in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 13:00:52
Suppose you have a table user_info containing the names of users and their addresses. An example is given below −nameaddressAnilAndheri, Mumbai, MaharashtraJoyChandni Chowk, DelhiRonBandra, Mumbai, MaharashtraReenaOld Airport Road, Bengaluru, KarnatakaNow, if you want to just extract the information of users who stay in Mumbai, you can do that using the LIKE command and the % operator.SELECT * from user_info where address LIKE '%Mumbai%'The output will benameaddressAnilAndheri, Mumbai, MaharashtraRonBandra, Mumbai, MaharashtraNotice that we have added % operator on both sides of Mumbai. This means that anything can precede Mumbai and anything can be after Mumbai. We just want the string to ... Read More

How to apply DISTINCT constraint on select columns in queries in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 12:57:26
Suppose you have a table exam_scores containing 5 columns. An example is given below with some dummy data.nameroll_nosubjecttotal_marksmarks_obtainedAnil1English10056Anil1Math10065Anil1Science10045Roy2English10078Roy2Math10098Roy2Science10067Now, one student could have sat for exams of multiple subjects, and therefore, there are multiple rows for 1 student. If you wish to find out the total number of students in the class, you may want to find the number of distinct values of roll_no. You can apply the distinct constraint on a specific column as follows −SELECT DISTINCT ON (roll_no) name, roll_no FROM exam_scores ORDER BY roll_no DESCHere’s what the output of the above query will look like −nameroll_noRoy2Anil1You can also ... Read More

CASE WHEN in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 12:55:49
If you are a programmer, you may be very familiar with IF-ELSE statements. The equivalent in PostgreSQL is CASE WHEN.Let’s understand with an example. If you have table marks containing percentage marks of a student, and you want to find out whether the students have passed or failed. An example table is given below.nameperc_marksAnil24Joy65Ron42Reena87Say the passing marks are 40. Now, if the student has scored above 40 marks, we want to print ‘PASS’ against that student’s name, otherwise ‘FAIL’. This is how you can do it −SELECT name, CASE WHEN perc_marks >= 40 THEN 'PASS' ELSE 'FAIL' END status from ... Read More

How to get current timestamp and relative timestamps in PostgreSQL?

Yash Sanghvi
Updated on 02-Feb-2021 12:54:56
Quite often, you need the current timestamp in PostgreSQL. You do that as follows −SELECT current_timestampIt will output the current time. The output will look like the following −2021-01-30 15:52:14.738867+00Now, what if you want the relative time instead of the current time? For example, if you want the time corresponding to 5 hours prior to the current time, you can get it using intervals.SELECT current_timestamp - interval '5 hours'The output will be different every time. At the time of writing this, the output was −2021-01-30 10:57:13.28955+00 You can also do these operations on date instead of timestampsSELECT current_dateOutput2021-01-30SELECT current_date + ... Read More