WEBVTT Kind: captions Language: en 00:00:01.170 --> 00:00:16.099 Sometimes, you may decide that you want to add or modify fields in your tables. 00:00:16.099 --> 00:00:19.751 Access makes it easy to do this, although there are some important things that you'll 00:00:19.751 --> 00:00:21.590 need to consider. 00:00:21.590 --> 00:00:25.230 There are three different rules that you can apply to control the type of data that the 00:00:25.230 --> 00:00:27.019 fields can accept. 00:00:27.019 --> 00:00:32.160 And these are data types, character limits, and validation rules. 00:00:32.160 --> 00:00:37.280 To get started, make sure that you have a table open. 00:00:37.280 --> 00:00:40.149 I'm using the Customers table. 00:00:40.149 --> 00:00:44.309 We're going to scroll all the way to the right until you see the blank field that says Click 00:00:44.309 --> 00:00:46.049 to Add. 00:00:46.049 --> 00:00:49.379 And when you click on it, you'll see a list of all of the data types that you can choose 00:00:49.379 --> 00:00:51.469 from. 00:00:51.469 --> 00:00:55.940 Text is the default option, and this is the type that you'll use for regular text, such 00:00:55.940 --> 00:00:58.499 as a person's name or address. 00:00:58.499 --> 00:01:02.199 You'll also use it for numbers that aren't used in calculations, like a phone number 00:01:02.199 --> 00:01:04.140 or zip code. 00:01:04.140 --> 00:01:08.680 For any numbers that you might want to do calculations with, you'll need to choose Number. 00:01:08.680 --> 00:01:12.880 For example, we would use this for the quantities of an item that were sold. 00:01:12.880 --> 00:01:16.350 If you're dealing with money, then you'll choose Currency. 00:01:16.350 --> 00:01:19.780 And if you choose Date & Time, then when you're editing that field, you'll see a calendar 00:01:19.780 --> 00:01:22.880 icon, which you can click to select a date. 00:01:22.880 --> 00:01:28.340 But in this case, I just want a simple Yes or No answer, so I'll choose this one. 00:01:28.340 --> 00:01:31.689 And this adds a checkbox for each record. 00:01:31.689 --> 00:01:33.890 Then you can type in the name of your field. 00:01:33.890 --> 00:01:38.869 I'm going to name it "Add to Mailing List?" 00:01:38.869 --> 00:01:42.890 Then I'll resize this field. 00:01:42.890 --> 00:01:48.000 Now we can just check each customer who wants to be on our mailing list. 00:01:48.000 --> 00:01:53.689 And you can also click and drag the name to move the field wherever you like. 00:01:53.689 --> 00:01:57.619 If you decide that you need a different data type for a field, then you can just select 00:01:57.619 --> 00:02:04.650 it, and then go to the Fields tab… and click the Data Type drop-down arrow. 00:02:04.650 --> 00:02:09.509 I'm going to change this to text so I can add additional information in this field. 00:02:09.509 --> 00:02:13.340 Some of our customers want to receive our weekly newsletter, but others just want to 00:02:13.340 --> 00:02:15.480 hear about our special events. 00:02:15.480 --> 00:02:19.670 Now you should be very careful about changing the data type because it is possible to lose 00:02:19.670 --> 00:02:23.530 some of your data if you change it to the wrong type. 00:02:23.530 --> 00:02:27.370 In some fields, you may want to narrow down the data even further by adding a character 00:02:27.370 --> 00:02:28.370 limit. 00:02:28.370 --> 00:02:31.090 And you can only do this with text fields. 00:02:31.090 --> 00:02:35.760 For example, we want all of the states to be formatted the same way, so we're only using 00:02:35.760 --> 00:02:38.290 the two-letter state abbreviations. 00:02:38.290 --> 00:02:43.069 If some of the records say NC, and others say North Carolina, then Access won't know 00:02:43.069 --> 00:02:48.670 to group them together—which means our sorts, filters, and queries may not work right. 00:02:48.670 --> 00:02:52.010 In the Fields tab, find the field size box. 00:02:52.010 --> 00:02:59.580 The default field size is 255 characters, but I'm going to change it to 2. 00:02:59.580 --> 00:03:02.750 And you may get a warning message here, so if you're sure you want to change the field 00:03:02.750 --> 00:03:05.769 size, click Yes. 00:03:05.769 --> 00:03:09.689 In this case, setting a character limit isn't quite good enough because somebody could still 00:03:09.689 --> 00:03:15.000 type a two-letter code that's not a real state (for example NX). 00:03:15.000 --> 00:03:18.850 To prevent that, we need to be a lot more specific about what types of input this field 00:03:18.850 --> 00:03:20.069 will accept. 00:03:20.069 --> 00:03:23.310 And we'll do that by adding a validation rule. 00:03:23.310 --> 00:03:29.390 In the Fields tab, go to the Validation command on the far right… and select Field Validation 00:03:29.390 --> 00:03:30.660 Rule. 00:03:30.660 --> 00:03:36.540 Here, I'm going to type each state abbreviation in quotation marks, and I'm separating each 00:03:36.540 --> 00:03:39.530 one with the word "Or." 00:03:39.530 --> 00:03:43.180 And this may take a while. 00:03:43.180 --> 00:03:48.650 So this expression is just looking for exact matches, but if you want, you can create validation 00:03:48.650 --> 00:03:52.780 rules using the same syntaxes that we talked about in the query lessons. 00:03:52.780 --> 00:03:56.790 For example, you could use the Like syntax to set a validation rule that only allows 00:03:56.790 --> 00:03:58.590 text that ends with "cake." 00:03:58.590 --> 00:04:03.170 Or, if you're using numerical values, you could use greater than to make sure that none 00:04:03.170 --> 00:04:07.290 of our quantities are negative. 00:04:07.290 --> 00:04:10.939 When you're done, click OK. 00:04:10.939 --> 00:04:15.750 Whenever you create a validation rule, it's important to create a validation message. 00:04:15.750 --> 00:04:19.880 And this option is also under the Validation command. 00:04:19.880 --> 00:04:23.470 This message will pop up whenever somebody tries to type in something that doesn't follow 00:04:23.470 --> 00:04:25.230 the validation rule. 00:04:25.230 --> 00:04:29.040 The message should briefly describe the rule, so that the user can then make the necessary 00:04:29.040 --> 00:04:30.040 corrections. 00:04:30.040 --> 00:04:36.840 In this case, I'll just mention that it needs to be a 2-letter abbreviation. 00:04:36.840 --> 00:04:41.010 Now you won't need to add a character limit or validation rule to all of your fields, 00:04:41.010 --> 00:04:44.790 but you can add one or both of them whenever you want to control the types of information 00:04:44.790 --> 00:04:46.190 that your field will accept.