WEBVTT Kind: captions Language: en 00:00:01.839 --> 00:00:14.180 Sometimes, you may decide that you want to add or modify fields in your tables. 00:00:14.180 --> 00:00:17.840 Access makes it easy to do this, although there are some important things that you'll 00:00:17.840 --> 00:00:19.660 need to consider. 00:00:19.660 --> 00:00:23.320 There are three different rules that you can apply to control the type of data that the 00:00:23.320 --> 00:00:25.100 fields can accept. 00:00:25.100 --> 00:00:30.170 And these are data types, character limits, and validation rules. 00:00:30.170 --> 00:00:35.090 To get started, make sure that you have a table open. 00:00:35.090 --> 00:00:37.980 I'm using the Customers table. 00:00:37.980 --> 00:00:42.120 We're going to scroll all the way to the right until you see the blank field that says Click 00:00:42.120 --> 00:00:43.870 to Add. 00:00:43.870 --> 00:00:47.210 And when you click on it, you'll see a list of all of the data types that you can choose 00:00:47.210 --> 00:00:48.579 from. 00:00:48.579 --> 00:00:53.760 Short text is the default option, and this is the type that you'll use for regular text, 00:00:53.760 --> 00:00:56.490 such as a person's name or address. 00:00:56.490 --> 00:01:00.180 You'll also use it for numbers that aren't used in calculations, like a phone number 00:01:00.180 --> 00:01:02.129 or zip code. 00:01:02.129 --> 00:01:06.670 For any numbers that you might want to do calculations with, you'll need to choose Number. 00:01:06.670 --> 00:01:10.859 For example, we would use this for the quantities of an item that were sold. 00:01:10.859 --> 00:01:14.340 If you're dealing with money, then you'll choose Currency. 00:01:14.340 --> 00:01:17.759 And if you choose Date & Time, then when you're editing that field, you'll see a calendar 00:01:17.759 --> 00:01:20.869 icon, which you can click to select a date. 00:01:20.869 --> 00:01:26.420 But in this case, I just want a simple Yes or No answer, so I'll choose this one. 00:01:26.420 --> 00:01:29.670 And this adds a checkbox for each record. 00:01:29.670 --> 00:01:31.869 Then you can type in the name of your field. 00:01:31.869 --> 00:01:37.289 I'm going to name it "Add to Mailing List?" 00:01:37.289 --> 00:01:41.649 Then I'll resize this field. 00:01:41.649 --> 00:01:46.759 Now we can just check each customer who wants to be on our mailing list. 00:01:46.759 --> 00:01:52.450 And you can also click and drag the name to move the field wherever you like. 00:01:52.450 --> 00:01:56.390 If you decide that you need a different data type for a field, then you can just select 00:01:56.390 --> 00:02:03.409 it, and then go to the Fields tab… and click the Data Type drop-down arrow. 00:02:03.409 --> 00:02:08.270 I'm going to change this to text so I can add additional information in this field. 00:02:08.270 --> 00:02:12.099 Some of our customers want to receive our weekly newsletter, but others just want to 00:02:12.099 --> 00:02:14.250 hear about our special events. 00:02:14.250 --> 00:02:18.430 Now you should be very careful about changing the data type because it is possible to lose 00:02:18.430 --> 00:02:21.879 some of your data if you change it to the wrong type. 00:02:21.879 --> 00:02:25.730 In some fields, you may want to narrow down the data even further by adding a character 00:02:25.730 --> 00:02:26.730 limit. 00:02:26.730 --> 00:02:29.670 And you can only do this with text fields. 00:02:29.670 --> 00:02:34.349 For example, we want all of the states to be formatted the same way, so we're only using 00:02:34.349 --> 00:02:36.890 the two-letter state abbreviations. 00:02:36.890 --> 00:02:41.659 If some of the records say NC, and others say North Carolina, then Access won't know 00:02:41.659 --> 00:02:47.260 to group them together—which means our sorts, filters, and queries may not work right. 00:02:47.260 --> 00:02:50.600 In the Fields tab, find the field size box. 00:02:50.600 --> 00:02:58.170 The default field size is 255 characters, but I'm going to change it to 2. 00:02:58.170 --> 00:03:01.340 And you may get a warning message here, so if you're sure you want to change the field 00:03:01.340 --> 00:03:04.390 size, click Yes. 00:03:04.390 --> 00:03:08.310 In this case, setting a character limit isn't quite good enough because somebody could still 00:03:08.310 --> 00:03:13.629 type a two-letter code that's not a real state (for example NX). 00:03:13.629 --> 00:03:17.470 To prevent that, we need to be a lot more specific about what types of input this field 00:03:17.470 --> 00:03:18.689 will accept. 00:03:18.689 --> 00:03:21.930 And we'll do that by adding a validation rule. 00:03:21.930 --> 00:03:28.020 In the Fields tab, go to the Validation command on the far right… and select Field Validation 00:03:28.020 --> 00:03:29.280 Rule. 00:03:29.280 --> 00:03:35.170 Here, I'm going to type each state abbreviation in quotation marks, and I'm separating each 00:03:35.170 --> 00:03:38.150 one with the word "Or." 00:03:38.150 --> 00:03:42.439 And this may take a while. 00:03:42.439 --> 00:03:47.900 So this expression is just looking for exact matches, but if you want, you can create validation 00:03:47.900 --> 00:03:52.040 rules using the same syntaxes that we talked about in the query lessons. 00:03:52.040 --> 00:03:56.040 For example, you could use the Like syntax to set a validation rule that only allows 00:03:56.040 --> 00:03:57.840 text that ends with "cake." 00:03:57.840 --> 00:04:02.430 Or, if you're using numerical values, you could use greater than to make sure that none 00:04:02.430 --> 00:04:06.540 of our quantities are negative. 00:04:06.540 --> 00:04:10.189 When you're done, click OK. 00:04:10.189 --> 00:04:14.999 Whenever you create a validation rule, it's important to create a validation message. 00:04:14.999 --> 00:04:19.150 And this option is also under the Validation command. 00:04:19.150 --> 00:04:22.720 This message will pop up whenever somebody tries to type in something that doesn't follow 00:04:22.720 --> 00:04:24.470 the validation rule. 00:04:24.470 --> 00:04:28.550 The message should briefly describe the rule, so that the user can then make the necessary 00:04:28.550 --> 00:04:29.550 corrections. 00:04:29.550 --> 00:04:36.229 In this case, I'll just mention that it needs to be a 2-letter abbreviation. 00:04:36.229 --> 00:04:40.389 Now you won't need to add a character limit or validation rule to all of your fields, 00:04:40.389 --> 00:04:44.180 but you can add one or both of them whenever you want to control the types of information 00:04:44.180 --> 00:04:45.590 that your field will accept.