Re: [PHP-DB] Tables and foreign keys
On Dec 26, 2011, at 1:57 AM, Amit Tandon wrote: Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.com wrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/ autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks Amit for the reply. Ok, so if you can not merge the two tables, then it is not a 1:1 relationship? EG: (table)CART: cartID - PRIMARY username firstname lastname product long description quantity options price (table)CARTDETAILS: cartdetailsID cartID - Foreign Key (Unique) product short description (taken from long des. in CART) quantity options price Is this a 1:1 if the key is between the two cartID's? What is actually happening when I make a foreign key? What does the foreign key cover? Just the row its linked to or the whole table? For this structure I would like, in order for their to be cartdetails, there should be a cart. If there is a cart then a cartdetails needs to automatically/ progmatically generate. (I think I read somewhere that MySQL is capable of doing this before sending back responses. Please correct me if I am wrong or if its unrelated.) What kind of relation is that? Also, if you or someone could explain what these cardinality rules mean. What.. 0 or 1 does? 1+ does? 0,1+does? Many (kind-of figured this one out, perhaps not.) etc.. I think that would help me greatly. I hope I am not sounding like a help vamp. I only ask because my google foo has failed me on where to search for these specific answers. Links are appreciated. I like to do stuff on my own but sometimes the brain cramps. :) TIA Best, Karl DeSaulniers Design Drumm http://designdrumm.com
Re: [PHP-DB] Tables and foreign keys
regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 1:55 PM, Karl DeSaulniers k...@designdrumm.comwrote: On Dec 26, 2011, at 1:57 AM, Amit Tandon wrote: Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.com wrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks Amit for the reply. Ok, so if you can not merge the two tables, then it is not a 1:1 relationship? EG: (table)CART: cartID - PRIMARY username firstname lastname product long description quantity options price (table)CARTDETAILS: cartdetailsID cartID - Foreign Key (Unique) product short description (taken from long des. in CART) quantity options price Is this a 1:1 if the key is between the two cartID's? No! it is 1:N becuase of Multiple rows in Cartid = 1 row in Cart What is actually happening when I make a foreign key? You link the two tables and try to find matching rows of cart in cart id What does the foreign key cover? Just the row its linked to or the whole table? The foreing key helps you uniquely identift set of rows. Foerign key actully help you identify the row(s). And then column of thos rows give you your value For this structure I would like, in order for their to be cartdetails, there should be a cart. If there is a cart then a cartdetails needs to automatically/progmatically generate. (I think I read somewhere that MySQL is capable of doing this before sending back responses. Please correct me if I am wrong or if its unrelated.) What kind of relation is that? Also, if you or someone could explain what these cardinality rules mean. What.. 0 or 1 does? 1:1 1+ does? 1:M 0,1+does? M:N - you figure correctly. But this is for both the tables i.e 1+ psosibility in both the tables. And this is generally table which is linked to two tables Many (kind-of figured this one out, perhaps not.) etc.. I think that would help me greatly. I hope I am not sounding like a help vamp. I only ask because my google foo has failed me on where to search for these specific answers. Links are appreciated. I like to do stuff on my own but sometimes the brain cramps. :) TIA Best, Karl DeSaulniers Design Drumm http://designdrumm.com
Re: [PHP-DB] Tables and foreign keys
On Dec 26, 2011, at 3:05 AM, Amit Tandon wrote: regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 1:55 PM, Karl DeSaulniers k...@designdrumm.com wrote: On Dec 26, 2011, at 1:57 AM, Amit Tandon wrote: Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.com wrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/ autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks Amit for the reply. Ok, so if you can not merge the two tables, then it is not a 1:1 relationship? EG: (table)CART: cartID - PRIMARY username firstname lastname product long description quantity options price (table)CARTDETAILS: cartdetailsID cartID - Foreign Key (Unique) product short description (taken from long des. in CART) quantity options price Is this a 1:1 if the key is between the two cartID's? No! it is 1:N becuase of Multiple rows in Cartid = 1 row in Cart What is actually happening when I make a foreign key? You link the two tables and try to find matching rows of cart in cart id What does the foreign key cover? Just the row its linked to or the whole table? The foreing key helps you uniquely identift set of rows. Foerign key actully help you identify the row(s). And then column of thos rows give you your value For this structure I would like, in order for their to be cartdetails, there should be a cart. If there is a cart then a cartdetails needs to automatically/ progmatically generate. (I think I read somewhere that MySQL is capable of doing this before sending back responses. Please correct me if I am wrong or if its unrelated.) What kind of relation is that? Also, if you or someone could explain what these cardinality rules mean. What.. 0 or 1 does? 1:1 1+ does? 1:M 0,1+does? M:N - you figure correctly. But this is for both the tables i.e 1+ psosibility in both the tables. And this is generally table which is linked to two tables So the 0=first table and ,1+ = subsezuent tables? Is there such thing as 1+,0? Or is that what 1+ is? Sry, the coma throws me off a bit. Many (kind-of figured this one out, perhaps not.) etc.. I think that would help me greatly. I hope I am not sounding like a help vamp. I only ask because my google foo has failed me on where to search for these specific answers. Links are appreciated. I like to do stuff on my own but sometimes the brain cramps. :) TIA Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks.. I think that got the knot out a little.. :) Best, Karl DeSaulniers Design Drumm http://designdrumm.com -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] Tables and foreign keys
Dear KarlRefer Wiki entryhttp://en.wikipedia.org/wiki/Entity-relationship_model. The last diagram shows one to many relationship in many ways. That may help you in clearing your doubts about the comma which is a way of representing the relationship Quoted from MS Access example One-To-Many Relationships A one-to-many relationship is the most common type of relationship. In this type of relationship, a row in table A can have many matching rows in table B, but a row in table B can have only one matching row in table A. For example, the Publishers and Titles tables have a one-to-many relationship: each publisher produces many titles, but each title comes from only one publisher. A one-to-many relationship is created if only one of the related columns is a primary key or has a unique constraint. Many-To-Many Relationships In a many-to-many relationship, a row in table A can have many matching rows in table B, and vice versa. You create such a relationship by defining a third table, called a junction table, whose primary key consists of the foreign keys from both table A and table B. For example, the Authors table and the Titles table have a many-to-many relationship that is defined by a one-to-many relationship from each of these tables to the TitleAuthors table. The primary key of the TitleAuthors table is the combination of the au_id column (the authors table’s primary key) and the title_id column (the Titles table’s primary key). One-To-One Relationships In a one-to-one relationship, a row in table A can have no more than one matching row in table B, and vice versa. A one-to-one relationship is created if both of the related columns are primary keys or have unique constraints. regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 2:43 PM, Karl DeSaulniers k...@designdrumm.comwrote: On Dec 26, 2011, at 3:05 AM, Amit Tandon wrote: regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 1:55 PM, Karl DeSaulniers k...@designdrumm.com wrote: On Dec 26, 2011, at 1:57 AM, Amit Tandon wrote: Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.com wrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks Amit for the reply. Ok, so if you can not merge the two tables, then it is not a 1:1 relationship? EG: (table)CART: cartID - PRIMARY username firstname lastname product long description quantity options price (table)CARTDETAILS: cartdetailsID cartID - Foreign Key (Unique) product short description (taken from long des. in CART) quantity options price Is this a 1:1 if the key is between the two cartID's? No! it is 1:N becuase of Multiple rows in Cartid = 1 row in Cart What is actually happening when I make a foreign key? You link the two tables and try to find matching rows of cart in cart id What does the foreign key cover? Just the row its linked to or the whole table? The foreing key helps you uniquely identift set of rows. Foerign key actully help you identify the row(s). And then column of thos rows give you your value For this structure I would like, in order for their to be cartdetails, there should be a cart. If there is a cart then a cartdetails needs to automatically/progmatically generate. (I think I read somewhere that MySQL is capable of doing this before sending back responses. Please correct me if I am wrong or if its unrelated.) What kind of relation is that? Also, if you or someone could explain what these cardinality rules mean. What.. 0 or 1 does? 1:1 1+ does? 1:M 0,1+does? M:N - you figure correctly. But this is for both the tables i.e 1+ psosibility in both the tables. And this is generally table which is linked to two tables So the 0=first table and ,1+ = subsezuent tables? Is there such thing as 1+,0? Or is that what 1+ is? Sry, the coma throws me off a bit. Many (kind-of figured this one out, perhaps
Re: [PHP-DB] Tables and foreign keys
Thank you! On Dec 26, 2011, at 4:12 AM, Amit Tandon wrote: Dear Karl Refer Wiki entry. The last diagram shows one to many relationship in many ways. That may help you in clearing your doubts about the comma which is a way of representing the relationship Quoted from MS Access example One-To-Many Relationships A one-to-many relationship is the most common type of relationship. In this type of relationship, a row in table A can have many matching rows in table B, but a row in table B can have only one matching row in table A. For example, the Publishers and Titles tables have a one-to-many relationship: each publisher produces many titles, but each title comes from only one publisher. A one-to-many relationship is created if only one of the related columns is a primary key or has a unique constraint. Many-To-Many Relationships In a many-to-many relationship, a row in table A can have many matching rows in table B, and vice versa. You create such a relationship by defining a third table, called a junction table, whose primary key consists of the foreign keys from both table A and table B. For example, the Authors table and the Titles table have a many-to-many relationship that is defined by a one-to-many relationship from each of these tables to the TitleAuthors table. The primary key of the TitleAuthors table is the combination of the au_id column (the authors table’s primary key) and the title_id column (the Titles table’s primary key). One-To-One Relationships In a one-to-one relationship, a row in table A can have no more than one matching row in table B, and vice versa. A one-to-one relationship is created if both of the related columns are primary keys or have unique constraints. regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 2:43 PM, Karl DeSaulniers k...@designdrumm.com wrote: On Dec 26, 2011, at 3:05 AM, Amit Tandon wrote: regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 1:55 PM, Karl DeSaulniers k...@designdrumm.com wrote: On Dec 26, 2011, at 1:57 AM, Amit Tandon wrote: Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.com wrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com Thanks Amit for the reply. Ok, so if you can not merge the two tables, then it is not a 1:1 relationship? EG: (table)CART: cartID - PRIMARY username firstname lastname product long description quantity options price (table)CARTDETAILS: cartdetailsID cartID - Foreign Key (Unique) product short description (taken from long des. in CART) quantity options price Is this a 1:1 if the key is between the two cartID's? No! it is 1:N becuase of Multiple rows in Cartid = 1 row in Cart What is actually happening when I make a foreign key? You link the two tables and try to find matching rows of cart in cart id What does the foreign key cover? Just the row its linked to or the whole table? The foreing key helps you uniquely identift set of rows. Foerign key actully help you identify the row(s). And then column of thos rows give you your value For this structure I would like, in order for their to be cartdetails, there should be a cart. If there is a cart then a cartdetails needs to automatically/ progmatically generate. (I think I read somewhere that MySQL is capable of doing this before sending back responses. Please correct me if I am wrong or if its unrelated.) What kind of relation is that? Also, if you or someone could explain what these cardinality rules mean. What.. 0 or 1 does? 1:1 1+ does? 1:M 0,1+does? M:N - you figure correctly. But this is for both the tables i.e 1+ psosibility in both the tables. And this is generally table which is linked to two tables So the 0=first table and ,1+ = subsezuent tables? Is there such thing as 1+,0? Or is that what 1+ is? Sry, the coma throws me off a bit. Many (kind-of figured this one out, perhaps not.) etc.. I
[PHP-DB] Tables and foreign keys
Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com
Re: [PHP-DB] Tables and foreign keys
Dear Karl Foreign key is a good option (provided you use InnoDB database) to automate the deletion/updation of cart details when you remove cart. Besides 1:1 cardinality is good or bad can only be decided on the semantics of your tables. As a an aside, if it is 1:1 cardinality, then you can probably merge the two tables regds amit The difference between fiction and reality? Fiction has to make sense. On Mon, Dec 26, 2011 at 12:38 PM, Karl DeSaulniers k...@designdrumm.comwrote: Hello all, I have two database tables. Cart and a cartdetails. I want the information for the cartdetails to be based on/autofilled info from cart. I want the ability to delete from cart and cartdetails to automatically clear as well. Would a foreign key be best suited for this? What kind of cardnaility would I use 1:1 ? Hope I make sense. Hope everyone had a great holidays! Best, Karl DeSaulniers Design Drumm http://designdrumm.com
