I have a table in that i have unique key .Now because of some reasons i want to update the unique key. AS of now unique key is having 4 columns now i want to add 2 more columns in that
CREATE TABLE abc (
id int(10) unsigned NOT NULL AUTO_INCREMENT,
one varchar(64) NOT NULL,
search_id varchar(64) NOT NULL,
session_id varchar(64) NOT NULL,
pnr varchar(64) NOT NULL,
origin varchar(5) NOT NULL,
destination varchar(5) NOT NULL,
type varchar(15) NOT NULL,
name1 varchar(55) NOT NULL,
name2 varchar(55) NOT NULL,
number varchar(55) DEFAULT '',
text text,
cr_dt timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (id),
UNIQUE KEY aedi_id (one,search_id,session_id,origin,destination,pnr,number) //I have this
UNIQUE KEY aedi_id (one,search_id,session_id,origin,destination,pnr,name1,name2,number) I want this
)
The syntax is:
alter table drop key aedi_id;
alter table add key aedi_id (one, search_id, session_id, origin, destination, pnr, name1, name2, number) ;
Note that a unique key is implemented as an index, which will be used for queries. This means that the order of the columns matters in the key definition -- some orderings will work better for your queries. So, depending on your queries, you may want to re-arrange the columns.
Related
In our mysql database, one table say "mytable" is having coumn mobile_no as primary key. But we are in need to make another column also as key. So that I can use that column in where condition.
Show create of table is below-:
CREATE TABLE `report_data` (
`api_request_id` int(11) NOT NULL AUTO_INCREMENT,
`emailid` varchar(100) NOT NULL,
`api_recipient_data` longtext,
`request_params` varchar(255) DEFAULT NULL,
`sent_date` date DEFAULT NULL,
`sent_time` datetime NOT NULL,
`status` tinyint(1) NOT NULL DEFAULT '0' COMMENT '1-processed, 2-success, 3-in-bounce, 4-invalid-domain,5-in-unsubscribe, 6-in-scrubbing',
`api_userid` int(11) DEFAULT NULL,
`domain_name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`api_request_id`,`emailid`),
KEY `sent_date` (`sent_date`)
);
I want to add one new column to this existing table and make that column as KEY.
we want to add one column d_name and want it to make it as KEY
ALTER TABLE report_data
ADD COLUMN d_name {column definition} ,
ADD INDEX (d_name);
sample fiddle
I am creating a database for selling houses.
I have a parent table that I am calling location that has three columns :
locationLat : the latitude of location of property
locationLong : the longitude of the property
locationName : an alternative name that i can use to identify the location of the property by name
Both locationLat and locationlong make up a composite primary key of this table.
Then I have a child table called houseToLet, this table only stores the houses that are for letting. I have similar different tables houseToBuy, fullyFurnished, landtoSell etc. The table for houseTolet has a composite primary key like the location table above i.e locationLat, locationLong and a foreign composite key location_locationLat and location_locationLong that references the location table.
Then I have another table called generalFeatures. This the table where I store general features of all the properties I am selling. So generalFeatures table is a child table of houseTolet and Housetobuy as well as Fullyfurnished tables,
When I insert rows into the location table, I find no problem as it is the parent table. When i insert rows into houseTolet table I find no problem since it is a child table and I will have inserted the parent location table already. However when I insert into the generalFeatures table I get into problem since it is a child table of housetoBuy as well as other tables including Fullyfurnished.
Please assist me to know how I can do this.
CREATE TABLE IF NOT EXISTS `foreign`.`location` (
`locationLat` DECIMAL(10,8) NOT NULL,
`locationLong` DECIMAL(11,8) NOT NULL,
`locationName` VARCHAR(35) NOT NULL,
PRIMARY KEY (`locationLat`, `locationLong`))
ENGINE = InnoDB
CREATE TABLE IF NOT EXISTS `location`.`housetolet` (
`locationLat` DECIMAL(10,8) NOT NULL,
`locationLong` DECIMAL(11,8) NOT NULL,
`type` ENUM('gatedCommunity', 'standalone', 'apartment') NOT NULL,
`location_locationLat` DECIMAL(10,8) NOT NULL,
`location_locationLong` DECIMAL(11,8) NOT NULL,
PRIMARY KEY (`locationLat`, `locationLong`),
INDEX `fk_housetolet_location_idx` (`location_locationLat` ASC, `location_locationLong` ASC))
CREATE TABLE IF NOT EXISTS `foreign`.`generalfeatures` (
`locationLat` DECIMAL(10,8) NOT NULL,
`locationLong` DECIMAL(11,8) NOT NULL,
`livingAreaAndSize` INT NOT NULL,
`bedrooms` TINYINT(4) NOT NULL,
`bathrooms` TINYINT(4) NOT NULL,
`masterEnsuite` TINYINT(1) NOT NULL,
`bedroomsWithBathrooms` TINYINT(4) NOT NULL,
`kitchenAndSize` TINYINT(4) NOT NULL,
`parkingAndSlots` TINYINT(4) NOT NULL,
`swimmingPool` TINYINT(1) NOT NULL,
`liftsAndNumber` TINYINT(4) NOT NULL,
`CCTV` TINYINT(1) NOT NULL,
`sizeOfLand` INT(11) NOT NULL,
`borehole` TINYINT(1) NOT NULL,
`housetobuy_locationLat` DECIMAL(10,8) NOT NULL,
`housetobuy_locationLong` DECIMAL(11,8) NOT NULL,
`housetolet_locationLat` DECIMAL(10,8) NOT NULL,
`housetolet_locationLong` DECIMAL(11,8) NOT NULL,
`fullyfurnished_locationLat` DECIMAL(10,8) NOT NULL,
`fullyfurnished_locationLong` DECIMAL(11,8) NOT NULL,
PRIMARY KEY (`locationLat`, `locationLong`),
INDEX `fk_generalfeatures_housetobuy1_idx` (`housetobuy_locationLat` ASC, `housetobuy_locationLong` ASC),
INDEX `fk_generalfeatures_housetolet1_idx` (`housetolet_locationLat` ASC, `housetolet_locationLong` ASC),
INDEX `fk_generalfeatures_fullyfurnished1_idx` (`fullyfurnished_locationLat` ASC, `fullyfurnished_locationLong` ASC),
CONSTRAINT `fk_generalfeatures_housetobuy1`
FOREIGN KEY (`housetobuy_locationLat` , `housetobuy_locationLong`)
REFERENCES `foreign`.`housetobuy` (`locationLat` , `locationLong`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_generalfeatures_housetolet1`
FOREIGN KEY (`housetolet_locationLat` , `housetolet_locationLong`)
REFERENCES `foreign`.`housetolet` (`locationLat` , `locationLong`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_generalfeatures_fullyfurnished1`
FOREIGN KEY (`fullyfurnished_locationLat` , `fullyfurnished_locationLong`)
REFERENCES `foreign`.`fullyfurnished` (`locationLat` , `locationLong`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
I want to be able to insert rows into generalFeatures table for houses to Let without getting foreign key constraints that I need to update other tables like houseTobuy or fullyFurnished first, this is because in a particular instance I will be updating a particular type of a house only but not many options. A house to let cannot be at the same time be a house to buy in my case.
Your database design has flaws. Namely, you are storing in multiple tables information that could be represented as a single record. As it is, it looks like all tables could be merged into main table locations :
the house* tables (houseToLet, houseToBuy, ...) are just there to store the current status of the location (to let, to buy, ...) : this could be represented as an ENUM field in the location table (or as several boolean columns if more than one status can be enabled at a time)
the generalFeatures table also seems to contain a single record for each location, hence all of its fields could be moved to the location table.
Using a single table appears like the right design for your use case (and it sure avoids issues with foreign constraints...).
Other considerations : use an autoincremented integer as primary key instead of a composite key (for this, you can create a UNIQUE constraint).
Here is a sample DDL for your table :
CREATE TABLE IF NOT EXISTS `foreign`.`location` (
-- primary key
`id` INT AUTO_INCREMENT,
PRIMARY KEY (`id`),
-- original columns
`locationLat` DECIMAL(10,8) NOT NULL,
`locationLong` DECIMAL(11,8) NOT NULL,
`locationName` VARCHAR(35) NOT NULL,
-- house status
`status` ENUM('toLet', 'houseToBuy', 'fullyFurnished', 'landtoSell') NOT NULL,
-- columns from `generalfeatures`
`livingAreaAndSize` INT NOT NULL,
`bedrooms` TINYINT(4) NOT NULL,
`bathrooms` TINYINT(4) NOT NULL,
`masterEnsuite` TINYINT(1) NOT NULL,
`bedroomsWithBathrooms` TINYINT(4) NOT NULL
-- other columns from `generalfeatures`...
)ENGINE = INNODB;
CREATE TABLE `journal` (
`yearr` int(4) NOT NULL,
`monthh` char(3) NOT NULL,
`volume` int(4) NOT NULL,
`issue` int(4) NOT NULL,
`pagefromto` varchar(10) NOT NULL,
`pissn` varchar(20) NOT NULL,
`eissn` varchar(20) DEFAULT NULL,
`name` varchar(50) NOT NULL,
`author1` varchar(10) DEFAULT NULL,
`author2` varchar(10) DEFAULT NULL,
`doc` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
)
ALTER TABLE `journal`
ADD PRIMARY KEY (`yearr`,`volume`,`issue`,`pagefromto`,`pissn`);
I need to add another key with auto increment to the above table structure
Your question is a bit confusing. You say you want to add a second primary key which will be auto increment... This doesn't make sense. They are called PRIMARY keys for a reason. There is only one primary key on a table as it is the, well, Primary key.
What I think you want to do is have a auto increment ID to use as the PK, which you could include in your create table like Arshad answered.
At that point, what you want to do is use your auto increment ID as the primary key (the same way you did with your PK, but put only the new ID in the PK, not the rest of your fields.), and you will want to use a unique index to make sure the combination of (yearr,volume,issue,pagefromto,pissn) doesn't repeat.
See this document to get more info on index creation
Note that if your table is already created, you'll have to delete the old primary key before you can add it on the ID.
You can use this query. This will create table with "id" as AutoIncrement and primary key
CREATE TABLE
tbl_employee (
id int(11) NOT NULL AUTO_INCREMENT,
employee_id int(4) NOT NULL,
employee_no int(6) NOT NULL,
employee_name varchar(60) NOT NULL,
department_id int(4) NOT NULL,
designation_id int(4) NOT NULL,
hired_date date NOT NULL,
salary int(10) NOT NULL,
PRIMARY KEY(id)
)
My Tables
Fee Table
CREATE TABLE IF NOT EXISTS `fee` (
`feeNumber` int(11) NOT NULL,
`feeName` varchar(255) NOT NULL,
`feeDescription` varchar(255) DEFAULT NULL,
`feeAmount` varchar(255) NOT NULL,
`universityName` varchar(255) NOT NULL
)
ADD PRIMARY KEY (`feeNumber`,`feeName`,`feeAmount`)
Housing Table
CREATE TABLE IF NOT EXISTS `housing` (
`housingOfficeNumber` int(11) NOT NULL,
`housingOfficeName` varchar(50) NOT NULL DEFAULT '',
`housingOfficeType` varchar(50) DEFAULT NULL,
`housingOfficePhone` decimal(18,0) DEFAULT NULL,
`housingOfficeRoomDeposit` varchar(50) DEFAULT NULL,
`studentStatusName` varchar(50) DEFAULT NULL,
`housingFeeNumber` int(11) NOT NULL,
`housingFeeName` varchar(255) NOT NULL,
`housingFee` int(255) DEFAULT NULL,
`hOffTrm` varchar(50) DEFAULT NULL,
`universityName` varchar(50) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
What I'm trying to do is reference the feeAmount,feeNumber, and feeName from the fee table and add it to the housingfee, housingfeeName, and housingFeenumber columns in the housing table. Since the feeAmount and feeName columns are not unique I decided to make a composite key out of feeNumber, feeName, and feeAmount. The only part of the composite key I really need referenced is feeAmount. feeName and feeNumber are not really important. using phpmyadmin.
No, no, no. In general, I think it is best to avoid compound primary keys. In this case, in particular, you do not want the fee amount or name to be part of the key. In order to access the row, you need to know the amount. That seems very difficult to implement.
I am guessing that an auto incremented primary key will work just fine. You can then add a separate unique constraint on other columns. So:
CREATE TABLE IF NOT EXISTS `fee` (
`feeNumber` int(11) NOT NULL auto_increment primary key,
`feeName` varchar(255) NOT NULL,
`feeDescription` varchar(255) DEFAULT NULL,
`feeAmount` varchar(255) NOT NULL,
`universityName` varchar(255) NOT NULL,
unique (feeName)
);
Then, another table would have feeNumber with an appropriate foreign key reference. Through the reference, you can get other information -- such as the name and amount -- using a join.
Say I'm setting up an small database with just 2 tables: feeds and feeditems.
In one table I'd store the feedname and url, with an ID as unique key.
In the second table I'd like to store some info coming from feed items (in example: date, title, url of the item and feedname). But instead of storing the feed name, I'd like to reference this feed field to the ID of that feed in the first table.
Thanks
this a quick example of how to achieve your requirement...
CREATE TABLE IF NOT EXISTS `feeds` (
`Feed_ID` int(11) NOT NULL,
`Feed_Name` varchar(32) NOT NULL,
`Feed_Url` varchar(255) NOT NULL,
PRIMARY KEY (`Feed_ID`)
)
CREATE TABLE IF NOT EXISTS `feeditems` (
`FeedItem_ID` int(11) NOT NULL,
`Feed_ID` int(11) NOT NULL,
`FeedItem_Date` datetime NOT NULL,
`FeedItem_Title` varchar(255) NOT NULL,
`FeedItem_Url` varchar(255) NOT NULL,
`FeedItem_Name` varchar(255) NOT NULL,
PRIMARY KEY (`FeedItem_ID`),
FOREIGN KEY (`Feed_ID`) REFERENCES `feeds`(`Feed_ID`)
ON DELETE CASCADE
)