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Database Articles
Page 432 of 546
Why does MySQL evaluate “TRUE or TRUE and FALSE” to true?
MySQL evaluates “TRUE or TRUE and FALSE” to true because AND has the highest priority than OR i.e. AND is evaluated before OR.The MySQL evaluates the above statement like this. The AND operator gets evaluated first −(TRUE or (TRUE AND FALSE))The statement (TRUE AND FALSE) gives the result FALSE. Then the second statement evaluates like this −(TRUE or FALSE)The above statement gives the result TRUE.Let us implement one by one −mysql> select (TRUE AND FALSE); +------------------+ | (TRUE AND FALSE) | +------------------+ | 0 | ...
Read MoreGet the count of duplicate values from a single column in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (0.83 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(10); Query OK, ...
Read MoreCan we use IN() to search between comma separated values within one field?
Instead of IN(), use FIND_IN_SET to search between comma separated values within one field. Let us first create a table −mysql> create table DemoTable -> ( -> ListOfValues text -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('10|20|30|40|50|60|100'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+-----------------------+ | ListOfValues | +-----------------------+ | 10|20|30|40|50|60|100 ...
Read MoreCan we return query results in same order as the values in MySQL `IN(…)` statement?
Yes, you can achieve this with ORDER BY FIELD() from MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(19); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(34); Query OK, 1 row affected (0.32 sec) mysql> insert into DemoTable values(28); Query OK, 1 row ...
Read MoreSplit a column after hyphen in MySQL and display the remaining value?
To split a column after hyphen, use the SUBSTRING_INDEX() method −select substring_index(yourColumnName, '-', -1) AS anyAliasName from yourTableName;Let us first create a table −mysql> create table DemoTable -> ( -> StreetName text -> ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Paris Hill St.-CA-83745646') ; Query OK, 1 row affected (0.32 sec) mysql> insert into DemoTable values('502 South Armstrong Street-9948443'); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> select *from ...
Read MoreHow to cut part of a string with a MySQL query?
For this, use substring_index() function from MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> StudentId varchar(100) -> ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('STU-1011'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('STU-95968686'); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+--------------+ | StudentId | +--------------+ | STU-1011 ...
Read MoreFinding the minimum and maximum value from a string with numbers separated by hyphen in MySQL?
Use MIN() function along with SUBSTRING() for minimum, whereas MAX() for maximum. Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value varchar(100) -> ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value) values('10-20'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(Value) values('200-100'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(Value) values('780-235'); Query OK, 1 row affected ...
Read MoreCan we implement 'LIKE' and ‘IN’ in a single MySQL query?
For more efficiency, use Regular Expression for the same task. Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(30) -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected ...
Read MoreHow to extract the area codes from a phone number with MySQL?
Let’s say we have a list of phone numbers and from that we want to get the area codes. These area codes are for example, the first 3 digits of the phone number. Use LEFT() function from MySQL for this.Let us first create a table −mysql> create table DemoTable -> ( -> AreaCodes varchar(100) -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command. Here, let’s say we have included the phone numbers −mysql> insert into DemoTable values('90387568976') ; Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('90389097878' ; ...
Read MoreBest data type for storing large strings in MySQL?
You can use text data type to store large strings. Following is the syntax −CREATE TABLE yourTableName ( yourColumnName text, . . N );Let us first create a table −mysql> create table DemoTable -> ( -> MyStringValue text -> ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('This is a text data type to store large string'); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from ...
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