fix: model interval qualifier as a structured property

src/main/java/net/sf/jsqlparser/expression/IntervalExpression.java

@@ -18,6 +18,7 @@ public class IntervalExpression extends ASTNodeAccessImpl implements Expression
     private final boolean intervalKeyword;
     private String parameter = null;
     private String intervalType = null;
+    private IntervalQualifier intervalQualifier = null;
     private Expression expression = null;
 
     public IntervalExpression() {
@@ -47,12 +48,42 @@ public void setParameter(String parameter) {
         this.parameter = parameter;
     }
 
+    /**
+     * Returns the non-standard single-identifier interval type (e.g. MySQL {@code INTERVAL 1 foo}),
+     * or {@code null} when a structured {@link IntervalQualifier} is present.
+     *
+     * @deprecated the structured {@link #getIntervalQualifier()} is the canonical representation.
+     *             This legacy field is kept only for the non-standard single-identifier form.
+     * @return the legacy interval type, or {@code null} if a qualifier is set
+     */
+    @Deprecated
     public String getIntervalType() {
         return intervalType;
     }
 
+    /**
+     * Sets the non-standard single-identifier interval type (e.g. MySQL {@code INTERVAL 1 foo}) and
+     * clears any structured qualifier.
+     *
+     * @deprecated use {@link #setIntervalQualifier(IntervalQualifier)} for the standard form.
+     * @param intervalType the legacy interval type
+     */
+    @Deprecated
     public void setIntervalType(String intervalType) {
         this.intervalType = intervalType;
+        this.intervalQualifier = null;
+    }
+
+    public IntervalQualifier getIntervalQualifier() {
+        return intervalQualifier;
+    }
+
+    /**
+     * Sets the structured interval qualifier and clears the legacy interval type.
+     */
+    public void setIntervalQualifier(IntervalQualifier intervalQualifier) {
+        this.intervalQualifier = intervalQualifier;
+        this.intervalType = null;
     }
 
     public Expression getExpression() {
@@ -67,7 +98,9 @@ public void setExpression(Expression expression) {
     public String toString() {
         return (intervalKeyword ? "INTERVAL " : "")
                 + Objects.toString(expression, parameter)
-                + (intervalType != null ? " " + intervalType : "");
+                + (intervalQualifier != null
+                        ? " " + intervalQualifier.toString()
+                        : (intervalType != null ? " " + intervalType : ""));
     }
 
     @Override
@@ -80,11 +113,22 @@ public IntervalExpression withParameter(String parameter) {
         return this;
     }
 
+    /**
+     * @deprecated use {@link #withIntervalQualifier(IntervalQualifier)} for the standard form.
+     * @param intervalType the legacy interval type
+     * @return this instance
+     */
+    @Deprecated
     public IntervalExpression withIntervalType(String intervalType) {
         this.setIntervalType(intervalType);
         return this;
     }
 
+    public IntervalExpression withIntervalQualifier(IntervalQualifier intervalQualifier) {
+        this.setIntervalQualifier(intervalQualifier);
+        return this;
+    }
+
     public IntervalExpression withExpression(Expression expression) {
         this.setExpression(expression);
         return this;

src/main/java/net/sf/jsqlparser/expression/IntervalQualifier.java

@@ -0,0 +1,123 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.expression;
+
+import java.io.Serializable;
+import java.util.Objects;
+
+/**
+ * Models an SQL interval qualifier as defined by the SQL standard (see
+ * <a href="https://www.postgresql.org/docs/current/datatype-datetime.html">PostgreSQL: Interval
+ * Input</a>), e.g. {@code YEAR}, {@code DAY TO SECOND}, {@code DAY(9) TO SECOND} or
+ * {@code SECOND(2, 4)}.
+ * <p>
+ * It is shared by {@link IntervalExpression} (the {@code INTERVAL ...} expression literal, used in
+ * DML) and by {@code net.sf.jsqlparser.statement.create.table.ColDataType} (the {@code INTERVAL}
+ * column / cast target type, used in DDL), so the qualifier is represented once and round-trips
+ * consistently across all contexts.
+ */
+public final class IntervalQualifier implements Serializable {
+
+    private final String leadingField;
+    private final Integer leadingFieldPrecision;
+    private final String trailingField;
+    private final Integer fractionalSecondsPrecision;
+
+    public IntervalQualifier(
+            String leadingField, Integer leadingFieldPrecision, String trailingField,
+            Integer fractionalSecondsPrecision) {
+        this.leadingField = leadingField;
+        this.leadingFieldPrecision = leadingFieldPrecision;
+        this.trailingField = trailingField;
+        this.fractionalSecondsPrecision = fractionalSecondsPrecision;
+    }
+
+    public String getLeadingField() {
+        return leadingField;
+    }
+
+    public Integer getLeadingFieldPrecision() {
+        return leadingFieldPrecision;
+    }
+
+    public String getTrailingField() {
+        return trailingField;
+    }
+
+    public Integer getFractionalSecondsPrecision() {
+        return fractionalSecondsPrecision;
+    }
+
+    public IntervalQualifier withLeadingField(String leadingField) {
+        return new IntervalQualifier(
+                leadingField, leadingFieldPrecision, trailingField, fractionalSecondsPrecision);
+    }
+
+    public IntervalQualifier withLeadingFieldPrecision(Integer leadingFieldPrecision) {
+        return new IntervalQualifier(
+                leadingField, leadingFieldPrecision, trailingField, fractionalSecondsPrecision);
+    }
+
+    public IntervalQualifier withTrailingField(String trailingField) {
+        return new IntervalQualifier(
+                leadingField, leadingFieldPrecision, trailingField, fractionalSecondsPrecision);
+    }
+
+    public IntervalQualifier withFractionalSecondsPrecision(Integer fractionalSecondsPrecision) {
+        return new IntervalQualifier(
+                leadingField, leadingFieldPrecision, trailingField, fractionalSecondsPrecision);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof IntervalQualifier)) {
+            return false;
+        }
+        IntervalQualifier that = (IntervalQualifier) o;
+        return Objects.equals(leadingField, that.leadingField)
+                && Objects.equals(leadingFieldPrecision, that.leadingFieldPrecision)
+                && Objects.equals(trailingField, that.trailingField)
+                && Objects.equals(fractionalSecondsPrecision, that.fractionalSecondsPrecision);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(
+                leadingField, leadingFieldPrecision, trailingField, fractionalSecondsPrecision);
+    }
+
+    /**
+     * Renders the qualifier back to SQL, e.g. {@code DAY}, {@code DAY TO SECOND},
+     * {@code DAY(9) TO SECOND} or {@code SECOND(2, 4)}.
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder(Objects.toString(leadingField, ""));
+        if (leadingFieldPrecision != null) {
+            sb.append("(").append(leadingFieldPrecision);
+            // For a single-field qualifier such as SECOND(2, 4), the fractional seconds
+            // precision is rendered together with the leading precision.
+            if (trailingField == null && fractionalSecondsPrecision != null) {
+                sb.append(", ").append(fractionalSecondsPrecision);
+            }
+            sb.append(")");
+        }
+        if (trailingField != null) {
+            sb.append(" TO ").append(trailingField);
+            if (fractionalSecondsPrecision != null) {
+                sb.append("(").append(fractionalSecondsPrecision).append(")");
+            }
+        }
+        return sb.toString();
+    }
+}

src/main/java/net/sf/jsqlparser/statement/create/table/ColDataType.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement.create.table;
 
+import net.sf.jsqlparser.expression.IntervalQualifier;
 import net.sf.jsqlparser.statement.select.PlainSelect;
 
 import java.io.Serializable;
@@ -26,6 +27,7 @@ public class ColDataType implements Serializable {
     private String dataType;
     private List<String> argumentsStringList;
     private String characterSet;
+    private IntervalQualifier intervalQualifier;
     private List<Integer> arrayData = new ArrayList<Integer>();
 
     public ColDataType() {
@@ -76,6 +78,14 @@ public void setCharacterSet(String characterSet) {
         this.characterSet = characterSet;
     }
 
+    public IntervalQualifier getIntervalQualifier() {
+        return intervalQualifier;
+    }
+
+    public void setIntervalQualifier(IntervalQualifier intervalQualifier) {
+        this.intervalQualifier = intervalQualifier;
+    }
+
     public List<Integer> getArrayData() {
         return arrayData;
     }
@@ -95,6 +105,7 @@ public String toString() {
             arraySpec.append("]");
         }
         return dataType
+                + (intervalQualifier != null ? " " + intervalQualifier.toString() : "")
                 + (argumentsStringList != null
                         ? " " + PlainSelect.getStringList(argumentsStringList, true, true)
                         : "")
@@ -117,6 +128,11 @@ public ColDataType withCharacterSet(String characterSet) {
         return this;
     }
 
+    public ColDataType withIntervalQualifier(IntervalQualifier intervalQualifier) {
+        this.setIntervalQualifier(intervalQualifier);
+        return this;
+    }
+
     public ColDataType withArrayData(List<Integer> arrayData) {
         this.setArrayData(arrayData);
         return this;
@@ -161,6 +177,7 @@ public final boolean equals(Object o) {
         return dataType.equalsIgnoreCase(that.dataType)
                 && Objects.equals(argumentsStringList, that.argumentsStringList)
                 && Objects.equals(characterSet, that.characterSet)
+                && Objects.equals(intervalQualifier, that.intervalQualifier)
                 && Objects.equals(arrayData, that.arrayData);
     }
 
@@ -169,6 +186,7 @@ public int hashCode() {
         int result = dataType.hashCode();
         result = 31 * result + Objects.hashCode(argumentsStringList);
         result = 31 * result + Objects.hashCode(characterSet);
+        result = 31 * result + Objects.hashCode(intervalQualifier);
         result = 31 * result + Objects.hashCode(arrayData);
         return result;
     }

src/main/java/net/sf/jsqlparser/util/deparser/ExpressionDeParser.java

@@ -1311,6 +1311,10 @@ public <S> StringBuilder visit(ExtractExpression extractExpression, S context) {
     }
 
     @Override
+    @SuppressWarnings("deprecation")
+    // The deparser must round-trip both the canonical IntervalQualifier and the deprecated
+    // legacy interval type (non-standard form such as MySQL INTERVAL 1 foo), so it reads
+    // getIntervalType() intentionally.
     public <S> StringBuilder visit(IntervalExpression intervalExpression, S context) {
         if (intervalExpression.isUsingIntervalKeyword()) {
             builder.append("INTERVAL ");
@@ -1320,7 +1324,9 @@ public <S> StringBuilder visit(IntervalExpression intervalExpression, S context)
         } else {
             builder.append(intervalExpression.getParameter());
         }
-        if (intervalExpression.getIntervalType() != null) {
+        if (intervalExpression.getIntervalQualifier() != null) {
+            builder.append(" ").append(intervalExpression.getIntervalQualifier().toString());
+        } else if (intervalExpression.getIntervalType() != null) {
             builder.append(" ").append(intervalExpression.getIntervalType());
         }
         return builder;