MySQL 5.7
I know squat about databases but I do have a custom program that uses the databases I have. If I want to use another account (twitter) with my program, I need to make all the datasets. I've done this a few times before. It always takes me a while to figure out, but I get there.
Yet this time I'm stuck with a read-only dataset.
What I usually do is I make a new schema with a proper name.
I then go to one of my other schemas, export what I need ('sources' and 'entries') and import them to my newly made schema.
That should work and it looked like it worked again this time. BUT there is a difference... It's read-only and I am way to green to tackle this on my own. I'll try to investigate a bit more myself, but some help sure would be appreciated : ) The warning is: "read only: the table has no unique row identifier (primary key or a NOT NULL unique index)": I couldn't find any results with this exact warning so I thought to post it here :)
Thank you!
Devvie
See my comments above on how to solve it.
TL;DL - if you are stuck with a read only schema after importing your data, you might want to tick the correct checkboxes for your schemas. Select schema, select Wrench Icon and match the table to be the same as the schema's table you imported from.
Thank you all.
Related
I'm and intern and I've been tasked with something I'm pretty unfamiliar with. My manager has requested I create a simple MySQL database using data from an Excel file(s) and I have no idea where to start. I would normally ask someone here for help but everyone seems to be really busy. Basically, the purpose of the database is to see what different object-groups relate to one another so as to keep things standardized. Trying not to go into detail about things not really relevant.
I was asked to first design a schema for the database and then I would get an update on how to implement it. Would I just start by writing queries to create tables? I'm assuming I would need to convert the Excel files to .csv, how do I read this data and send it to the correct table based on Object Type (an attribute of each object, represented in a column)?
I don't want to ask too much right now, but if someone could help me understand what I need to do to get started I would really appreciate it.
Look at the column headers in your spread sheet.
Decide which columns relate to Objects and which columns relate to Groups
The columns that relate to just Objects will become your field names for the Object table. Give this table an ID field so you can uniquely identify each Object.
The columns that relate to the Groups will become field names for a Group table. Give this table an ID field so you can uniquely identify each Group.
Think about if an Object can be in more than one Group - if so you will probably need an Object-Group table. This table would most likely contain an ObjectID and a GroupID.
I am flummoxed that no one seems to have ever asked this question, which indicates that the question itself is flawed. But, I don't know how to find out the right question, or answer, other than asking, so here goes:
I'm trying out a couple of tools to connect to MySQL databases and view and edit the data. So far I've tried MySQL Workbench and Database Browser. MySQL Workbench seems to be much more robust and lets you set up foreign keys without having to write any SQL.
The problem, though, is that when inserting and updating data in columns that are foreign keys, I have to manually enter the numeric id of the parent row, and once entered, I have to manually look up which record that number refers to if I want to know. Is there no way to set a display field in the parent table and then be able to choose a value off a dropdown menu when editing the child table? phpMyAdmin does this. I'm perplexed that, not only can't I find a way to achieve this in any non-web-based database tool (I've tried Access before, too), but that no one seems ever to have needed to do it before. Am I completely thinking about this wrong? Do people not use these tools to do this type of work? Is everyone writing their own custom lookup interfaces from scratch in Qbasic? Should I memorize all the ids for my parent rows?
Or are people laughing up their sleeves at this question because it's framed so awkwardly?
SQLYog provides such functionality
https://blog.webyog.com/wp-content/uploads/2011/04/FK-Dropdown1.png
I have to build this retail site, and aparently all the properties info comes from a third party company. Everything looked fine, they sent me a .mdb file with all the tables (which convert to a .sql file), and later I get emailed with data to update those tables.
What confused me was the fact that a few of these tables already have values in them. And when looking at the documentation, it says that I will also get emailed 'dictionary tables'. It says: "These tables contain fixed values in reference to value tables".
I have googled and searched here at stalkoverflow but couldnt find an answer. What I read was something about 'sas' and 'proc sql' which I haven't heard before.
Could someone please explain me (or kindly point me to some understandable documentation) what this tables are (are they in fact tables?), and how can I use them to build my site? I also use Codeigniter, can I use active records on them? Or what would be the correct SQL to access that table? I'm pretty much lost here :(
I use Codeigniter 2.x and Mysql.
Thanks guys, I will be infinetely grateful for your help.
Two guesses:
a data dictionary provides information about tables in a database:
field names, field types, field sizes
stored procedures associated with certain tables
OR
simply a fixed table that provides lookup or validation for a separate updatable table.
I'm teaching myself Delphi database programming using a MySQL database. I'm trying to add a record from a nested ClientDataSet with the link between master and detail tables an autoincrement field in the master table. I found a question/answer pair that appears to answer my question at: Inserting records with autoincrementing primary keys
The thing I don't understand is setting the required flag in the Query. I can't figure out how to do that as I'm too inexperienced, nor do I understand why it is necessary.
Similar to the question linked above, I have a
(SQLConnection->TSQLDataSet->DataSetProvider->ClientDataSet using dbexpress.
| |->LinkDataSource
->TSQLDataSet2->LinkDataSource
I load data into my nested ClientDataSet fine, so the component links to create the nested structure work. After loading the master/detail tables into the nested dataset, the following code gives an error.
MasterCDS1.Append;
MasterCDS1.FieldByName('TLNo').Required := False;
MasterSDS.FieldByName('TLNo').Required := False; { Error: Field 'TLNo' not found }
MasterCDS1.FieldByName('TLNo').ProviderFlags := [pfInWhere, pfInKey];
{ ... Populate Master table Fields}
MasterCDS1.Post;
MasterCDS1.ApplyUpdates(0);
TLNo is the field linking the tables and part of the primary key of the master table, and part of the primary key of the detail table. The third line where I try to set the TSQLDataSet generates the error shown in the comment. MasterSDS is where I put my 'Select * from master' query. MasterCDS learns the Schema from this query and that the field TLNo is a required field in both master and detail MySQL tables. That third line of code is my "interpretation" of what Mr Uwe Raabe said to do. Clearly I did this wrong. Can someone provide a code example so that this Delphi noob won't misinterpret the instructions? Thanks in advance.
The only reason I can imagine for the error you describe is that MasterSDS is not open when you execute that third line. "Field not found" raises either when the field does not exist in the table or the dataset (i.e. query in this case) is not open and has no static fields defined.
This leads to another point I want to mention: place the Required and the ProviderFlags settings in the AfterOpen event of the corresponding dataset. There is no need to repeat these settings whenever you append a record. If you work with static fields you can even do these settings in the Object Inspector.
For being a starter I suggest you always use static fields which can be adjusted inside the IDE. This will simplify things significantly.
I have defined three tables, Stores, InventoryItems and StoreItemRecords. My StoreItemRecords table has foreign key columns (StoreID, InventoryItemID) that "point to" the primary keys of the Stores (StoreID) and InventoryItems (InventoryItemID) records. The columns are named the same between the tables.
If I run a query like this:
SELECT StoreID, InventoryItemID FROM StoreItemRecords;
I get some bizarre results. I get:
1, Hammer
2, Box of Nails
3, Some other item name.
So, I am getting the StoreID, as I should. But I am also getting the NAME of the inventory item, not the ID of the inventory item. Also, it is important to note that the InventoryItemID column is defined as a NUMBER, not TEXT.
So somehow, Access is trying to help me by providing the InventoryItemName in place of the InventoryItemID, but I can't seem to find the cause of this behavior or any way to stop it.
[one more note. I have written some VBA code to populate the StoreItemRecords table and, in debug mode, I can "watch" the InventoryItemID values being assigned to the column, and I have verified that the IDs are actually being put in there.]
Has anyone seen behavior like this? I know I am going to feel really dumb when someone points out the goofy thing I am doing to cause this but, at this point, it is worth the embarrassment.
Thanks in advance for any help you can provide.
My money is on one of the fields being setup as a “lookup table” in access. These are generally considered to be a not so useful feature of access trying to help novice developers who find it hard to grasp how a database works.
If you go into the table in design mode you should be able to verify if that is set on the fields in question. If it is turn it off and try the query again
Here is a link on why they are evil
http://www.mvps.org/access/lookupfields.htm